Information recording medium having substrate with microscopic pattern and reproducing apparatus therefor

ABSTRACT

A recording medium includes a substrate having a microscopic pattern, which includes a shape of continuous substance of approximately parallel grooves formed with a convex shaped section and a concave shaped section alternating on a surface of the substrate. A recording layer is formed on the microscopic pattern and a light transmitting layer has a thickness of 0.05 mm to 0.12 mm formed on the recording layer. The microscopic pattern satisfies a relation of P≦λ/NA, wherein P is a pitch of the convex shaped section, λ is a wavelength of a reproducing light beam and NA is a numerical aperture of an objective lens. The microscopic pattern also includes modulated address information formed on both side walls of the convex shaped section viewed from the light transmitting layer as a wobble, both the side walls being parallel to each other, and furthermore wherein the address information is modulated by the phase-shift keying modulation system. A reproducing apparatus is particularly suited for the recording medium.

This application is a Continuation of application Ser. No. 11/008,405,filed on Dec. 10, 2004 now U.S. Pat. No. 7,139,236, which is aDivisional of application Ser. No. 10/728,960, filed on Dec. 8, 2003(now U.S. Pat. No. 6,873,595), which is a Divisional of application Ser.No. 10/135,844, filed on May 1, 2002 (now U.S. Pat. No. 6,693,873); andfor which priority is claimed under 35 U.S.C. § 120; and thisapplication claims priority of Application No. 2002-125978 filed inJapan on Apr. 26, 2002 under 35 U.S.C. § 119, and Application No.2001-134954 filed in Japan on May 2, 2001 under 35 U.S.C. § 119; theentire contents of all are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording medium usedfor a reproducing apparatus and a recording apparatus, which read outinformation from the information recording medium with making it moverelatively, particularly, relates to an information recording medium tobe recorded and/or reproduced by an optical device.

2. Description of the Related Art

Until now, recording and reproducing information by using a laser beamor like has been performed by an optical disc system.

There existed a DVD (Digital Versatile Disc) as one of informationrecording mediums used for such an optical disc system. Such a DVD dischas an information recording surface composed of an information trackand an information pit array, which are engraved in a rugged shape on asurface of a transparent plastic substrate having a thickness of 0.6 mmand a diameter of 120 mm by a forming process. The information track isprovided for recording information, and the information pit array isprovided for reproducing the information by scanning the pit array.

In a case of a reproducing type information recording medium, areflective layer composed of a high reflectivity film such as gold andaluminum is formed on an information recording surface. Further, in acase of a recording type information recording medium, a dye film isformed on the information recording surface.

With respect to a recording type information recording medium formedwith a dye film on the information recording surface, there is provideda DVD-R (Digital Versatile Disk-Recordable) as a recordable informationrecording medium. Furthermore, there is provided a rewritableinformation recording medium, which is formed with magneto-opticalrecording film on the information recording surface.

FIG. 32 is a cross sectional view of a conventional recording type DVD-Rdisc.

Such a DVD-R disc mentioned above is actually composed a structure shownin FIG. 32. In FIG. 32, a DVD-R disc 70 is composed of a transparentplastic substrate 71 having an information recording surface 710 on itssurface, a recording layer 72, an adhesive layer 73 and a dummysubstrate 74. The recording layer 72 and the adhesive layer 73 arelaminated on the substrate 71 in order, and then the dummy substrate 74is affixed on the adhesive layer 73. The information recording layer 710is further composed of an information track and an information pitarray, which are engraved in a rugged shape.

Generally, a convex shaped section, which projects into a side to beirradiated by a laser beam for recording and reproducing, is applied foran information track. In the convex shaped section, an information trackcomposed of a groove and address information composed of a pit areformed as a continuous line or as an intermittent pit array with respectto a scanning direction of a laser beam. These information track andaddress information are formed by a forming method of a so-calledstamper method. The intermittent pit array is provided for a user torecord information in a predetermined information track accurately bypositioning the predetermined information track.

According to a manufacturing method of recording type DVD-R disc by thestamper method, an information track and address information, which areformed by a cutting method, are provided in a concave shaped section“AA” of the substrate 71 as shown in FIG. 32.

The recording type DVD-R disc 70 is recorded and reproduced byirradiating a laser beam “LB” having a wavelength of 635 nm on theinformation recording surface 710 from the substrate 71 side. In otherwords, the laser beam “LB” is irradiated on the concave shaped section“AA” of the substrate 71, and then the recording type DVD-R disc isrecorded and reproduced.

The concave shaped section “AA” and a convex shaped section “BB” of thesubstrate 71 are referred to as a groove and a land respectively.

FIG. 33 is a cross sectional view of a next generation type informationrecording medium having higher density than a current DVD disc. Such anext generation type information recording medium has been developedactively. In FIG. 33, a next generation type information recordingmedium 75 in high density is composed of a substrate 71 having aninformation recording surface 710 in a rugged shape on its surface, arecording layer 72 and a light transmitting layer 76 having a thicknessof 0.1 mm, wherein they are laminated in order. The substrate 71 is madeof a transparent plastic disc having a thickness of 1.1 mm and adiameter of 120 mm and manufactured by the stamper method as the samemethod as for a DVD disc. The next generation type information recordingmedium 75 is recorded and reproduced by irradiating a laser beam “LB”having a wavelength of 400 nm on an information track of the informationrecording surface 710 and a concave shaped section “AA” or a groove ofthe substrate 71.

That is to say, in either of the recording type DVD-R disc 70 and thenext generation type information recording medium 75, recording andreproducing is performed with respect to the concave shaped section “AA”on the substrate 71. When viewing from a different angle, in the case ofthe recording type DVD-R disc 70, information is recorded on andreproduced from a concave shaped section, which projects into a side tobe irradiated by a laser beam for recording and reproducing. On thecontrary, in the case of the next generation type information recordingmedium 75, information is recorded on and reproduced from a convexshaped section, which becomes dented with respect to a side to beirradiated by a laser beam for recording and reproducing.

In other words, a groove to be an information track becomes projectedinto a side to be irradiated by a laser beam for recording andreproducing with respect to the recording type DVD-R disc. However, inthe case of the next generation type information recording medium 75,the groove becomes dented with respect to a side to be irradiated by thelaser beam.

Inventors of the present invention have actually performed recording andreproducing of such a next generation type information recording medium75 in high density. The inventors founded a problem such that an outputof reproduced signal has decreased and resulted in deterioration ofinformation quality and an error rate of reproduced signal increasedwhen information has been recorded in the concave shaped section “AA”,which is a groove of the substrate 71, in comparison with recording andreproducing the convex shaped section “BB”, which is a land of thesubstrate 71.

Further, since an information signal recorded in the concave shapedsection “AA” has been deteriorated in quality, recording in high densitycould not be performed. Such deterioration of quality is supposed to becaused by that a direction of thermal diffusion in the recording layer72 turns around.

In order to deal with the phenomenon, it is considered that informationis recorded on the convex shaped section “BB” as a land and reproduced.However, an address to be reproduced were interfered and resulted inanother problem such that accurate address information itself could notbe reproduced.

SUMMARY OF THE INVENTION

Accordingly, in consideration of the above-mentioned problems of theprior art, an object of the present invention is to provide aninformation recording medium and a manufacturing method thereof, whereinan reproduced signal in high output and high quality can be obtainedfrom the information recording medium and address information can beread out accurately from the information recording medium even thoughthe information recording medium is used by irradiating a laser beam onthe surface that is opposite to the substrate.

Further, another object of the present invention is to provide areproducing apparatus and a recording apparatus for recording andreproducing such an information recording medium.

In order to achieve the above object, the present invention provides,according to an aspect thereof, an information recording medium at leastcomprising: a substrate having a microscopic pattern, which isconstituted by a shape of continuous substance of approximately parallelgrooves formed with a convex shaped section and a concave shaped sectionalternately on a surface of the substrate; a recording layer formed onthe microscopic pattern; and a light transmitting layer having thicknessof 0.05 mm to 0.12 mm formed on the recording layer, the microscopicpattern satisfies a relation of P≦λ/NA, wherein P is a pitch of theconvex shaped section or the concave shaped section, λ is wavelength ofreproducing light beam and NA is a numerical aperture of an objectivelens, and further the microscopic pattern is characterized in thatmodulated address information is formed on both side walls of the convexshaped section viewed form the light transmitting layer side as a wobblehaving same period and phase.

According to another aspect of the present invention, there provided aninformation recording medium at least comprising: a substrate having amicroscopic pattern, which is constituted by a shape of continuoussubstance of approximately parallel grooves formed with a convex shapedsection and a concave shaped section alternately on a surface of thesubstrate; a recording layer formed on the microscopic pattern; and alight transmitting layer having thickness of 0.05 mm to 0.12 mm formedon the recording layer, the microscopic pattern satisfies a relation ofP≦λ/NA, wherein P is a pitch of the convex shaped section or the concaveshaped section, λ is a wavelength of reproducing light beam and NA is anumerical aperture of an objective lens, and further the microscopicpattern is characterized in that a modulated address information isformed on both side walls of the convex shaped section viewed form thelight transmitting layer side as a wobble being parallel to each other.

Other object and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross sectional view of information recording medium showinga first step (preparing a substrate) of a manufacturing method ofinformation recording medium according to an embodiment of the presentinvention.

FIG. 2 is a cross sectional view of information recording medium showinga second step (forming an energy ray sensitive film) of themanufacturing method of information recording medium according to theembodiment of the present invention.

FIG. 3 is a cross sectional view of information recording medium showinga third step (forming a first microscopic pattern) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 4 is a cross sectional view of information recording medium showinga fourth step (forming a first plating layer) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 5 is a cross sectional view of information recording medium showinga fifth step (producing a first plating die) of the manufacturing methodof information recording medium according to the embodiment of thepresent invention.

FIG. 6 is a cross sectional view of information recording medium showinga sixth step (forming a second plating layer) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 7 is a cross sectional view of information recording medium showinga seventh step (producing a second plating die) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 8 is a cross sectional view of information recording medium showingan eighth step (producing a substrate) of the manufacturing method ofinformation recording medium according to the embodiment of the presentinvention.

FIG. 9 is a cross sectional view of information recording medium showinga ninth step (forming a recording layer) of the manufacturing method ofinformation recording medium according to the embodiment of the presentinvention.

FIG. 10 is a cross sectional view of an information recording mediummanufactured by the manufacturing method shown in FIGS. 1 through 9.

FIG. 11 is a plan view, partially enlarged, of the information recordingmedium shown in FIG. 10.

FIG. 12 is a cross sectional side view of a first energy ray radiatingapparatus for recording a microscopic pattern on an informationrecording medium according to the present invention.

FIG. 13 is a cross sectional side view of a second energy ray radiatingapparatus for recording a microscopic pattern on an informationrecording medium according to the present invention.

FIG. 14 is a cross sectional view of a negative type energy raysensitive film in a producing process of a plated die in a negative typeaccording to the embodiment of the present invention.

FIG. 15 is a cross sectional view of a negative type substrate in aforming process of negative type substrate according to the embodimentof the present invention.

FIG. 16 is a fragmentary plan view, partially enlarged, of a microscopicpattern formed on an information recording medium, which is manufacturedby the manufacturing method of information recording medium according toembodiment of the present invention.

FIG. 17 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV (ContinuousLinear Velocity) recording in a disc shape, according to the presentinvention.

FIG. 18 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV recording in adisc shape and recorded by a user, according to the present invention.

FIG. 19 shows a first amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 20 shows a second amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 21 shows a third amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 22 shows a first frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 23 shows a second frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 24 shows a third frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 25 shows a first phase-shift keying modulation waveform recorded ona fourth microscopic pattern.

FIG. 26 shows a second phase-shift keying modulation waveform recordedon a fourth microscopic pattern.

FIG. 27 shows a third phase-shift keying modulation waveform recorded ona fourth microscopic pattern.

FIG. 28 is a block diagram of a first reproducing apparatus according tothe embodiment of the present invention.

FIG. 29 is a plan view of a photo detector installed in the reproducingapparatus shown in FIG. 28.

FIG. 30 is a block diagram of a second reproducing apparatus accordingto the embodiment of the present invention.

FIG. 31 is a block diagram of a recording apparatus according to theembodiment of the present invention.

FIG. 32 is a cross sectional view of a conventional recording type DVD-Rdisc.

FIG. 33 is a cross sectional view of a next generation type informationrecording medium having higher density than a current DVD disc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

With referring to FIGS. 1 through 31, an embodiment of the presentinvention will be explained.

FIG. 1 is a cross sectional view of information recording medium showinga first step (preparing a substrate) of a manufacturing method ofinformation recording medium according to an embodiment of the presentinvention.

FIG. 2 is a cross sectional view of information recording medium showinga second step (forming an energy ray sensitive film) of themanufacturing method of information recording medium according to theembodiment of the present invention.

FIG. 3 is a cross sectional view of information recording medium showinga third step (forming a first microscopic pattern) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 4 is a cross sectional view of information recording medium showinga fourth step (forming a first plating layer) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 5 is a cross sectional view of information recording medium showinga fifth step (producing a first plating die) of the manufacturing methodof information recording medium according to the embodiment of thepresent invention.

FIG. 6 is a cross sectional view of information recording medium showinga sixth step (forming a second plating layer) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 7 is a cross sectional view of information recording medium showinga seventh step (producing a second plating die) of the manufacturingmethod of information recording medium according to the embodiment ofthe present invention.

FIG. 8 is a cross sectional view of information recording medium showingan eighth step (producing a substrate) of the manufacturing method ofinformation recording medium according to the embodiment of the presentinvention.

FIG. 9 is a cross sectional view of information recording medium showinga ninth step (forming a recording layer) of the manufacturing method ofinformation recording medium according to the embodiment of the presentinvention.

FIG. 10 is a cross sectional view of an information recording mediummanufactured by the manufacturing method shown in FIGS. 1 through 9.

FIG. 11 is a plan view, partially enlarged, of the information recordingmedium shown in FIG. 10.

FIG. 12 is a cross sectional side view of a first energy ray radiatingapparatus for recording a microscopic pattern on an informationrecording medium according to the present invention.

FIG. 13 is a cross sectional side view of a second energy ray radiatingapparatus for recording a microscopic pattern on an informationrecording medium according to the present invention.

FIG. 14 is a cross sectional view of a negative type energy raysensitive film in a producing process of a plated die in a negative typeaccording to the embodiment of the present invention.

FIG. 15 is a cross sectional view of a negative type substrate in aforming process of negative type substrate according to the embodimentof the present invention.

FIG. 16 is a fragmentary plan view, partially enlarged, of a microscopicpattern formed on an information recording medium, which is manufacturedby the manufacturing method of information recording medium according toembodiment of the present invention.

FIG. 17 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV (ContinuousLinear Velocity) recording in a disc shape, according to the presentinvention.

FIG. 18 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV recording in adisc shape and recorded by a user, according to the present invention.

FIG. 19 shows a first amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 20 shows a second amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 21 shows a third amplitude-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 22 shows a first frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 23 shows a second frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 24 shows a third frequency-shift keying modulation waveformrecorded on a fourth microscopic pattern.

FIG. 25 shows a first phase-shift keying modulation waveform recorded ona fourth microscopic pattern.

FIG. 26 shows a second phase-shift keying modulation waveform recordedon a fourth microscopic pattern.

FIG. 27 shows a third phase-shift keying modulation waveform recorded ona fourth microscopic pattern.

FIG. 28 is a block diagram of a first reproducing apparatus according tothe embodiment of the present invention.

FIG. 29 is a plan view of a photo detector installed in the reproducingapparatus shown in FIG. 28.

FIG. 30 is a block diagram of a second reproducing apparatus accordingto the embodiment of the present invention.

FIG. 31 is a block diagram of a recording apparatus according to theembodiment of the present invention.

(Process for Preparing Flat Substrate)

As shown in FIG. 1, a flat substrate 1 is prepared for a first step ofmanufacturing an information recording medium according to the presentinvention.

The flat substrate 1 is finished in flat as fine as the optical gradeand selected out of a ceramic substrate such as silicon oxide,non-alkali glass and 7913 glass, and a metal substrate having silicon,molybdenum, tungsten or their alloy (including alloy oxide, nitride orcarbide) on the surface of the metal substrate.

(Process for Forming Energy Ray Sensitive Film)

As shown in FIG. 2, a positive type energy ray sensitive film 2 iscoated on one surface of the flat substrate 1.

The positive type energy ray sensitive film 2 is a material having acharacteristic such as decomposing or polymerizing when irradiated withan energy ray. It is applicable for the decomposing process to becomposed of either one step or a plurality of steps (for example, two orthree steps, or more steps).

The decomposing process of the positive type energy ray sensitive film 2by one through three steps or more steps is explained next.

With respect to a typical example of decomposing process by one step, ina case that an energy ray is deep-ultraviolet radiation in highilluminance, resin such as polycarbonate resin and polystyrene resin canbe used for the positive type energy ray sensitive film 2 and formedwith a hole by sublimation or explosion phenomenon on a surface of theresin.

Further, as another example of decomposing process by one step, in acase that an energy ray is ultraviolet radiation represented by the“g-line” ray (having a wavelength of 436 nm) in high illuminance ordeep-ultraviolet radiation having a shorter wavelength than 436 nm, athin film such as tellurium oxide thin film, vanadium oxide thin film,molybdenum oxide thin film, yttrium oxide thin film, palladium oxidethin film, silver oxide thin film, tungsten oxide thin film and zincoxide thin film can be used for the positive type energy ray sensitivefilm 2 and can be formed with a hole by sublimating a surface of thinfilm.

With respect to a typical example of decomposing process by two steps,in a case that an energy ray is ultraviolet radiation, a film formedwith a mixed material of cresol novolac resin and naphthoquinone diazidecan be used for the positive type energy ray sensitive film 2. Byirradiating the energy ray on the surface of the film, naphthoquinonediazide decomposes chemically and releases cresol novolac resin frominsolubility. At this moment, the film has no hole on the surface.However, letting alkaline development solution flow on the surface ofthe film solves an irradiated portion of the film. Consequently, a holecan be formed on the surface of the film.

With respect to a typical example of decomposing process by three steps,in a case that an energy ray is deep-ultraviolet radiation or anelectron beam, a film, which is at least composed of polyhydroxy styreneresin and acid generating agent such as onium salt, can be used for thepositive type energy ray sensitive film 2. By irradiating an energy rayon the surface of the film, acid generating agent decomposes chemicallyand generates acid. At this moment, the film has no hole on the surface.However, upon being heated, the acid diffuses throughout the film andthe polyhydroxy styrene resin is decomposed. Then, letting alkalinedevelopment solution flow on the surface of the film solves anirradiated portion of the film. Consequently, a hole can be formed onthe surface of the film.

In addition thereto, a negative type energy ray sensitive film of whicha portion influenced by converged energy ray becomes insoluble can beused in stead of a positive type energy ray sensitive film 2. In a caseof using a negative type energy ray sensitive film, by increasing ordecreasing a number of plating processes by one step, unlike a positivetype energy ray sensitive film, such a negative type energy raysensitive film can comply with the manufacturing method of the presentinvention. A manufacturing method that uses a negative type energy raysensitive film as the energy ray sensitive film 2 will be depictedlater.

(Process for Forming Microscopic Pattern)

In FIG. 3, by using an energy ray radiating apparatus 30 or 40 shown inFIG. 12 or 13, a converged energy ray, which is controlled by aprocessor (not shown), is irradiated on the positive type energy raysensitive film 2. As shown in FIG. 3, a groove “G” having an addresswobble and a land “L” are formed and then, a first microscopic pattern 3shown in FIGS. 3 and 11 is formed. While forming the first microscopicpattern 3, both sides of the groove “G” is formed so as to be equal toeach other in wobbling period and phase.

Actually, the groove “G” of the first microscopic pattern 3 is formed byswinging the converged energy ray right and left or by changingirradiation strength of the converged energy ray in conjunction withswinging it right and left in accordance with address information. Theright and left mentioned above is a direction that is at right angle toa progressing direction of the groove “G”. In other words, the directionof right and left is a direction that intersects perpendicularly to atrack direction. In a case that an information recording medium 11 shownin FIG. 10, which is manufactured by transferring the first microscopicpattern 3, is in disciform, for example, the direction of right and leftis a radial direction of the information recording medium 11. Theinformation recording medium 11 itself will be detailed later.

A portion, which is irradiated with a converged energy ray, on theenergy ray sensitive film 2 is hereinafter referred to as a groove “G”.

With referring to FIGS. 12 and 13, first and second energy ray radiatingapparatuses 30 and 40 are explained next.

FIG. 12 is a cross sectional side view of a first energy ray radiatingapparatus for recording a microscopic pattern on an informationrecording medium according to the present invention.

As shown in FIG. 12, the first energy ray radiating apparatus 30 iscomposed of a flat substrate supporting unit 110, which supports theflat substrate 1 formed with the energy ray sensitive film 2, an energyray radiating unit 120 and a relative motion supplying unit 100.

The flat substrate supporting unit 110 is a unit that can support theflat substrate 1 having the energy ray sensitive film 2 at least duringa period of time while recording by irradiating an energy ray. Actually,such a unit is equivalent to a table, which is polished in higheraccuracy and equipped with fixing mechanism (such as screwing, vacuumsuction and electrostatic suction) so as to install the flat substrate1.

The energy ray radiating unit 120 is further composed of an energy raysource 121, which radiates an energy ray, a beam shaper 122, whichshapes the energy ray in a beam shape suitable for information recordingby signal modulation and resulted in a converged energy ray 200, and areflecting mirror 123 that conducts the converged energy ray 200, whichis signal modulated by the beam shaper 122, to the flat substrate 1formed with the energy ray sensitive film 2 that is installed on theflat substrate supporting unit 110. Further, a processor (not shown),which generates and transmits a modulation signal in accordance withaddress information, is connected to the beam shaper 122. In thisconstitution, a lens (not shown) can be install between the flatsubstrate supporting unit 110 and the reflecting mirror 123 so as toconverge the energy ray.

The energy ray source 121 radiates an electromagnetic wave having awavelength of 10 nm to 1500 nm (such as γ-ray, X-rays, extremelydeep-ultraviolet, deep-ultraviolet, ultraviolet, visible radiation andinfrared radiation) and a particle beam (such as α-ray, β-ray, protonbeam, neutron beam and electron beam).

As an actual example of the energy ray source 121, there is existed aradiating apparatus that radiates a wide range of energy rays coveringfrom ultraviolet to deep-ultraviolet having a wavelength (such as 364nm, 355 nm, 351 nm, 325 nm, 275 nm, 266 nm, 257 nm, 248 nm and 244 nm).

With respect to an actual example of the beam shaper 122, there isexisted an electrooptical deflection apparatus (EOD) by anelectrooptical crystal element and an acoustooptic deflection apparatus(AOD) by acoustooptic crystal element. Further, in a case that theenergy ray source 121 is a radiating apparatus, which radiates anelectron beam, the beam shaper 122 is defined to be a blanking electrodeand a beam deflection apparatus.

The reflecting mirror 123 is provided for conducting the convergedenergy ray 200 to the flat substrate 1, which is formed with the energyray sensitive film 2. Therefore, if the energy ray radiating unit 120 isin a constitution such that the converged energy ray 200 can beirradiated on the flat substrate 1 having the energy ray sensitive filmdirectly, the reflecting mirror 123 is not necessary for the firstenergy ray radiating apparatus 30.

A circuit, which can delay, reduce or expand a time period betweenreceiving and transmitting address information, can be built in aprocessor (not shown) or installed between the processor and the beamshaper 122 in accordance with necessity.

The relative motion supplying unit 100 is composed of a motor and lineardriving mechanism and can perform various movements such as rotating,X-axis directional moving, Y-axis directional moving and Z-axisdirectional moving or combined movement of them.

By installing a position monitor in accordance with necessity, therelative motion supplying unit 100 can be controlled according to amonitored position. Further, the relative motion supplying unit 100 isallocated on either one side of the energy ray radiating unit 120 andthe flat substrate supporting unit 110, or both sides of them. In thisembodiment, the relative motion supplying unit 100 is allocated on theside of the energy ray radiating unit 120 and moves the energy rayradiating unit 120 relatively.

With referring to FIG. 13, a second energy ray radiating apparatus 40 isexplained next.

FIG. 13 is a cross sectional side view of the second energy rayradiating apparatus 40 for recording a microscopic pattern on aninformation recording medium according to the present invention.

In FIG. 13, the second energy ray radiating apparatus 40 is in aconstitution that a relative motion supplying unit 100A, which isequivalent to the relative motion supplying unit 100 of the first energyray radiating apparatus 30, is disposed under the flat substratesupporting unit 110. The flat substrate 1 formed with the energy raysensitive film 2 is moved relatively by the relative motion supplyingunit 100A.

By using the first and second energy ray radiating apparatuses 30 and40, an actual forming method of the first microscopic pattern 3 shown inFIGS. 3 and 11 by a spot “ES” of the converged energy ray 200 isdetailed next.

In a case that the first energy ray radiating apparatus 30 is used, theflat substrate 1 formed with the energy ray sensitive film 2 isinstalled on the flat substrate supporting unit 110. A groove “G” havingan address wobble, which is composed of a concave section, is formed onthe flat substrate 1 by irradiating the converged energy ray 200 on thepositive type energy ray sensitive film 2 while the flat substrate 1 ismoved relatively, wherein the converged energy ray 200 is radiated bythe energy ray source 121 in the energy ray radiating unit 120 and issignal modulated by the beam shaper 122, and then reflected by thereflecting mirror 123.

Forming the groove “G” is realized by utilizing interaction between thepositive type energy ray sensitive film 2 and the converged energy ray200.

In other words, by irradiating the spot “ES” of the converged energy ray200 (hereinafter simply referred to as spot “ES”) on the positive typeenergy ray sensitive film 2, the first microscopic pattern 3 that isformed with the groove “G” having a plurality of address wobbles and theland “L”, which is adjacent to the groove “G”, can be obtained. Asmentioned above, the groove “G” is a concave shaped section and the land“L” is a convex shaped section.

Further, a decomposition process of the positive type energy raysensitive film 2 can be evolved by one step or a plurality of steps.Therefore, in a case of using the positive type energy ray sensitivefilm 2 in one step, the first microscopic pattern 3 is formedimmediately after the converged energy ray 200 is irradiated on thepositive type energy ray sensitive film 3. On the contrary, in a case ofthe plurality of steps, by processing predetermined treatment (forexample, in a case of two steps, the treatment is an alkaline developingtreatment, and in a case of three steps, it is heating and alkalinedeveloping treatment), the first microscopic pattern 3 that is composedof the groove “G” and the land “L”, which are alternately repeated, canbe obtained.

Furthermore, in a case of forming the groove “G” linearly, as mentionedabove, it is realized by moving either one of the flat substratesupporting unit 110 and the energy ray radiating unit 120. More, byusing relative motion between the flat substrate supporting unit 110 andthe energy ray radiating unit 120, a uniform track pitch “P” can also bemaintained.

While forming the groove “G” linearly, an address wobble is actuallyformed by swinging the position to be continuously irradiated with theconverged energy ray 200 right and left. As mentioned above, the “rightand left” is a direction that is at right angle to a progressingdirection of the groove “G”. In other words, the direction of “right andleft” is a direction that intersects perpendicularly to a trackdirection.

In a surrounding area of the converged energy ray 200 that isirradiated, a position perpendicular to the progressing direction of thegroove “G” is corresponding to both sides of the groove “G” to beformed. Therefore, by swinging the converged energy ray 200 to thedirection that is at right angle to the progressing direction of thegroove “G”, both sides of the groove “G” wobble and a wobbling groove“G” in uniform period and phase is formed. The wobbling groove “G” is inuniform period and phase, so that both sides of the groove “G” that isformed in the first microscopic pattern 3 are always in parallel to eachother.

In addition thereto, the wobbling groove “G” can be formed by changingirradiating strength of the converged energy ray 200 in conjunction withswinging the converged energy ray 200 right and left. The timing ofchanging and swinging the converged energy ray 200 can be controlled byan address information controlling mechanism (not shown). For example,irradiating the converged energy ray 200 while address information is ONforms a groove “G” having an address wobble in the energy ray sensitivefilm 2 on the flat substrate 1.

In a case of using the second energy radiating apparatus 40, the firstmicroscopic pattern 3 shown in FIGS. 3 and 11 is formed by the sameprocesses as those of the first energy ray radiating apparatus 30 exceptfor moving the relative motion supplying unit 100A relatively whileoperating the flat substrate supporting unit 110.

In FIGS. 3 and 11, the flat substrate 1 formed with the firstmicroscopic pattern 3 is called a cutting master.

In this embodiment of the present invention, address information formedon a groove “G” is an address that changes continuously at a position onan information recording medium 11 shown in FIG. 10, which will beexplained later. The address information is data that is selected outfrom absolute address, which is allocated to whole area of theinformation recording medium 11, relative address, which is allocated toa partial area, track number, sector number, frame number, field numberand time information. These data change incrementally or decrementcontinuously in accordance with progressing of a recording track (groove“G”, for example). In addition to the address information, specificinformation that is composed of a small amount of data can be formedtogether with the address information.

The specific information is common data in the whole area of theinformation recording medium 11. The common data is at least selectedout from information related to the information recording medium such asclassification of the information recording medium, size of theinformation recording medium, supposed recording capacity of theinformation recording medium, supposed recording linear density of theinformation recording medium, supposed recording linear velocity of theinformation recording medium, track pitch of the information recordingmedium, recording strategy information, reproduction power information,manufacture information, manufacturing number, lot number, controlnumber, copyright related information, key for producing cryptograph,key for deciphering, ciphered data, recording permission code, recordingrefusal code, reproduction permission code and reproduction refusalcode, for example.

It is acceptable that these address and specific information areinformation, which is described by the decimal number system or thehexadecimal number system and converted into the binary number system(such as the BCD code and the gray code). Further, it is also acceptablethat the address and specific information are accompanied by an errorcorrection code for preventing data from error.

The address information is formed by wobbling of groove “G” as mentionedabove. A signal, which is supplied to the beam shaper 122, istransmitted from the processor (not shown) that generates a modulationsignal in accordance with digital data of address information. In a casethat the address information is in digital, the modulation signal to begenerated is constituted by any one of the amplitude-shift keyingmodulation wave 250 (250, 251 and 252), the frequency-shift keyingmodulation wave 260 (260, 261 and 262) and the phase-shift keyingmodulation wave 270 (270, 271 and 272) or by any one of them that aretransformed.

These modulation systems will be detailed later. By the amplitude-shiftkeying modulation system, an address is expressed in digital data (suchas “1” and “0”) in response to whether a fundamental wave is existed ornot, or amplitude strength exceeds a predetermined value or not. In acase of the frequency-shift keying modulation system, an address isexpressed in digital data (such as “1” and “0”) in response to afrequency of the fundamental wave, whether the frequency is higher orlower. In a case of the phase shift modulation system, an address isexpressed in digital data (such as “1” and “0”) in response to a phaseangle difference of the fundamental wave (for example, a phase angledifference of fundamental wave at each interval of one period).

By adopting these modulation systems, an address can be formed in highefficiency. A fundamental wave of these modulations can be selected outfrom any of a sine wave (or a cosine wave), a triangular wave and arectangular wave. If a sine wave (or a cosine wave) is selected out fromthem, a harmonic component can be minimized when reproducing andresulted in improving electric power efficiency and suppressing jitter.Therefore, a sine wave (or a cosine wave) is suitable for a fundamentalwave.

The address is formed by the first or second energy ray radiatingapparatus 30 or 40 such that the spot “ES” is modulated to a directionperpendicularly to a progressing direction of a track in accordance witha modulation system. In other words, a direction of time axis ofmodulation signal is transformed to a track direction of groove “G” andfurther an amplitude direction of the modulation signal is transformedto a direction perpendicular to the groove “G”, and then the address isformed.

(Process for Forming First Plating Layer)

As shown in FIG. 4, a first plating layer 4 is formed over the flatsubstrate 1 having the first microscopic pattern 3.

In a case that either the positive type energy ray sensitive film 2 orthe flat substrate 1 is conductive, the first plating layer 4 is formedby plating directly on the surface of the positive type energy raysensitive film 2. Further, in a case that either one of the positivetype energy ray sensitive film 2 and the flat substrate 1 isnonconductor or semiconductor, a thin conductive film (not shown) isformed on the surface of the positive type energy ray sensitive film 2as pretreatment, and then the first plating layer 4 is formed on thethin conductive film through a plating process.

Hereinafter, the thin conductive film is considered to be a part of thefirst plating layer 4.

Nickel and cobalt having thickness within a rage of 100 μm to 500 μm,more desirably 200 μm to 400 μm, and most desirably 240 μm to 310 μm, oran alloy that contain nickel or cobalt can be used for the first platinglayer 4.

A metal such as nickel, nickel-palladium alloy, nickel-phosphorus alloy,nickel-boron alloy, nickel-phosphorus-boron alloy, gold, silver,silver-palladium alloy and silver-palladium-copper alloy havingthickness within a range of 50 nm to 150 nm, desirably about 100 nm canbe used for the thin conductive film. In accordance with necessity, areinforcing plate can be adhered on a surface of the first plating layer4 that is opposite to the positive type energy ray sensitive film 2. Aplate such as glass, aluminum and stainless steel having thicknesswithin a range of 0.3 mm to 20 mm can be used for such a reinforcingplate.

(Process for Producing First Plating Die)

As shown in FIG. 5, a first plating die 5 is produced by peeling off thefirst plating layer 4 from the flat substrate 1 that is formed with thepositive type energy ray sensitive film 2.

The peeling off is performed physically along the boundary between thepositive type energy ray sensitive film 2 and the first plating layer 4.In a case of having the thin conductive film as mentioned above, thepeeling off can be applied to the boundary between the thin conductivefilm and the first plating layer 4. If the peeling off is processedchemically, residue of the positive type energy ray sensitive film 2that is adhered on the first plating film 4 can be reduced and the firstplating die 5 having less defective second microscopic pattern 3A can beobtained.

The second microscopic pattern 3A on the first plating die 5 that ispeeled off from the flat substrate 1 is reversely arranged to the firstmicroscopic pattern 3 that is formed by the “process for formingmicroscopic pattern” as mentioned above in a relationship betweenconcave and convex.

Further, in consideration of a succeeding “process for formingsubstrate”, a total shape of the first plating die 5 can be modifiedwhile a shape of the second microscopic pattern 3A in the first platingdie 5 is maintained.

(Process for Forming Second Plating Layer)

As shown in FIG. 6, a second plating layer 6 is formed on the firstplating die 5 that is formed with the second microscopic pattern 3A.

(Process for Producing Second Plating Die)

As shown in FIG. 7, peeling off the second plating layer 6 from thefirst plating die 5 produces a second plating die 7 that is formed witha third microscopic pattern 3B.

In this process, the third microscopic pattern 3B of the second platingdie 7 is identical to the first microscopic pattern 3 that is formed bythe “process for forming microscopic pattern” in a relationship betweenconcave and convex.

(Process for Forming Substrate)

As shown in FIG. 8, a fourth microscopic pattern 3C is formed bytransferring the third microscopic pattern 3B of the second plating die7 to a substrate 8.

In this process, commonly known forming methods such as injectionmolding, compression molding, injection compression molding and 2P(Photo Polymerization) molding can be used for forming the substrate 8having the fourth microscopic pattern 3C. The fourth microscopic pattern3C formed on the substrate 8 is reversely arranged to the firstmicroscopic pattern 3 formed on the flat substrate 1 in a relationshipbetween concave and convex.

With respect to a material of the substrate 8, a synthetic resin is usedfor the substrate 8. Typical examples of the synthetic resin are asfollows: various thermoplastic and thermosetting resins such aspolycarbonate, polymethyle methacrylate, polystyrene, copolymer ofpolycarbonate and polystyrene, polyvinyl chloride, alicyclic polyolefinand polymethyle pentene, and various energy ray curable resins(including examples of ultraviolet (UV) ray curable resins, visibleradiation curable resins and electron beam curable resins). They can beused suitably.

Further, these materials can be applicable to be a synthetic resin thatis combined with metal powder or ceramic powder. Due to necessity ofsupporting an information recording medium mechanically, thickness ofthe substrate 8 is within a range of 0.3 mm to 3 mm, desirably 0.5 mm to2 mm. Furthermore, in a case that an information recording medium 11shown in FIG. 10, which will be explained later, is in disciform,thickness of the substrate 8 is most desirable to be designed such thattotal thickness of the information recording medium 11, which iscomposed of the substrate 8, a recording layer 9 (refer to FIG. 9) and alight transmitting layer 10 (refer to FIG. 10), becomes 1.2 mm inconsideration of interchangeability with a conventional optical disc.

(Process for Forming Recording Layer)

As shown in FIG. 9, a recording layer 9 is formed on the fourthmicroscopic pattern 3C of the substrate 8.

The recording layer 9 is a thin film layer having functions such asreading out information, recording information or rewriting information.With respect to a material for the recording layer 9, there is provideda phase change material, which induces a change of reflectivity, achange of refractive index or both of them before and after recording, amagneto-optical material, which induces a change of Kerr rotation anglebefore and after recording, and a dye material, which induces a changeof refractive index, a change of depth or both of them before and afterrecording.

With respect to an actual example of phase change material, alloyscomposed of an element such as indium, antimony, tellurium, selenium,germanium, bismuth, vanadium, gallium, platinum, gold, silver, copper,aluminum, silicon, palladium, tin and arsenic are used, (wherein analloy includes a compound such as oxide, nitride, carbide, sulfide andfluoride). Particularly, alloys composed of a system such as Ge—Sb—Tesystem, Ag—In—Te—Sb system, Cu—Al—Sb—Te system and Ag—Al—Sb—Te systemare suitable for the recording layer 9. These alloys can contain one ormore elements as a micro additive element within a range of more than0.01 atomic % and less than 10 atomic % in total. Such a micro additiveelement is selected out of Cu, Ba, Co, Cr, Ni, Pt, Si, Sr, Au, Cd, Li,Mo, Mn, Zn, Fe, Pb, Na, Cs, Ga, Pd, Bi, Sn, Ti, V, Ge, Se, S, As, Tl andIn.

With respect to compositions of each element, for example, there isexisted Ge₂Sb₂Te₅, Ge₁Sb₂Te₄, Ge₈Sb₆₉Te₂₃, Ge₈Sb₇₄Te₁₈, Ge₅Sb₇₁Te₂₄,Ge₅Sb₇₆Te₁₉, Ge₁₀Sb₆₈Te₂₂ and Ge₁₀Sb₇₂Te₁₈ as for the Ge—Sb—Te systemand a system adding a metal such as Sn and In to the Ge—Sb—Te system asfor the Ge—Sb—Te system. Further, as for the Ag—In—Sb—Te system, thereis existed Ag₄In₄Sb₆₆Te₂₆, Ag₄In₄Sb₆₄Te₂₈, Ag₂In₆Sb₆₄Te₂₈,Ag₃In₅Sb₆₄Te₂₈, Ag₂In₆Sb₆₆Te₂₆, and a system adding a metal orsemiconductor such as Cu, Fe and Ge to the Ag—In—Sb—Te system.

With respect to an actual example of magneto-optical material, alloyscomposed of an element such as terbium, cobalt, iron, gadolinium,chromium, neodymium, dysprosium, bismuth, palladium, samarium, holmium,praseodymium, manganese, titanium, erbium, ytterbium, lutetium and tincan be used, (wherein an alloy includes a compound such as oxide,nitride, carbide, sulfide and fluoride). Particularly, constituting analloy of a transition metal, which is represented by TbFeCo, GdFeCo andDyFeCo, with rare earth element is preferable. Further, the recordinglayer 9 can be constituted by using an alternate lamination layer ofcobalt and platinum.

With respect to an actual example of dye material, porphyrin dye,cyanine dye, phthalocyanine dye, naphthalocyanine dye, azo dye,naphthoquinone dye, fulgide dye, polymethine dye and acridine dye can beused.

With respect to a forming method of the recording layer 9, a filmforming method such as a vapor phase film forming method and a liquidphase film forming method can be used. As a typical example of the vaporphase film forming method, such methods as vacuum deposition of resisterheating type or electron beam type, direct current sputtering, highfrequency sputtering, reactive sputtering, ion beam sputtering, ionplating and chemical vapor deposition (CVD) can be used. Further, withrespect to a typical example of the liquid phase film forming methodsuch as spin coating method and dipping and drawing up method can beused.

(Process for Forming Light Transmitting Layer)

As shown in FIG. 10, an information recording medium 11 is manufacturedby forming a light transmitting layer 10 on the recording layer 9, whichis produced through the processes shown in FIGS. 1 through 9.

A concave shaped section, which sinks to the light transmitting layer 10side with observing from the substrate 8 side, is equivalent to thegroove “G” that is formed by a converged energy ray in the process forforming a microscopic pattern shown in FIG. 3, as a result.

Consequently, wobble signals of both sides of the groove “G” can beunified so as to have the same period and phase when reproducing therecording layer 9 formed on the groove “G” of the information recordingmedium 11 by irradiating a laser beam “LB” from the light transmittinglayer 10 side as shown in FIG. 10.

The light transmitting layer 10 is composed of a material havingfunction of conducting converged reproducing light to the recordinglayer 9 with keeping the converged reproducing light in less opticaldistortion. For example, a material having transmittance of more than70% at a reproduction wavelength λ, preferably more than 80% can besuitably used for the light transmitting layer 10. It is essential forthe light transmitting layer 10 to be less optical anisotropy. In orderto suppress reduction of reproducing light, actually, a material havingbirefringence of less than ±100 nm, preferably ±50 nm by 90-degree(vertical) incident double paths and in a sheet shape having thicknesswithin a range of 50 μm to 120 μm, preferably 70 μm to 100 μm is usedfor the light transmitting layer 10.

With respect to a material in a sheet shape having such a birefringencecharacteristic, a synthetic resin such as polycarbonate, polymethylemethacrylate, cellulose triacetate, cellulose diacetate, polystyrene,copolymer of polycarbonate and polystyrene, polyvinyl chloride,alicyclic polyolefin and polymethyle pentene can be used for the lighttransmitting layer 10 in a sheet shape.

Further, a material having high stiffness can also be used for the lighttransmitting layer 10. For example, transparent ceramics (such as sodalime glass, soda aluminosilicate glass, borosilicate glass and silicaglass), thermosetting resin, energy ray curable resin (such asultraviolet rays curable resin, visible radiation curable resin andelectron beam curable resin), moisture curable resin and two-part liquidmixture curable resin are preferably used for the light transmittinglayer 10 having high stiffness.

Furthermore, the light transmitting layer 10 is not limited to a singlelayer. A plurality of layers that is combined by those materials can beapplied to the light transmitting layer 10.

With respect to a forming method of the light transmitting layer 10, ina case that the light transmitting layer 10 is constituted by a singlelayer of sheet shaped material, a heat welding method is utilized. In acase that the light transmitting layer 10 is constituted by a singlelayer of various curable resins, a spin coating method, a screenprinting method, a roll coating method or a knife coating method can beutilized.

The light transmitting layer 10 can also be constituted by two layers ofa sheet shaped material and various curable resins. In this case, thereexisted a method that is constituted by several processes such assandwiching any of various curable resins between the light transmittinglayer 10 and the recording layer 9, spinning off excessive curableresin, and then thin-filming the curable resin and adhering themtogether by centrifugal force.

A fluctuation amount of thickness of the light transmitting layer 10 inone surface is desirable to be ±0.003 mm maximum in consideration ofspherical aberration of the information recording medium 11 whenreproducing. Particularly, in a case that numerical aperture (NA) ofobjective lens is more than 0.85, the fluctuation amount is desirable tobe less than ±0.002 mm. Further, in a case that NA of an objective lensis 0.9, the fluctuation amount is desirable to be less than ±0.001 mm.

According to the embodiment of the present invention, as mentionedabove, the information recording medium 11 is manufactured by theprocess constituting the “process for forming first plating layer”through the “process for forming second plating die” by using thepositive type energy ray sensitive film 2. Therefore, each wobblingperiod and phase of both sides of the land “L” on the substrate 8 can beunified.

As a result, an information recording medium 11 in which an informationtrack is equivalent to a concave section that projects into the lighttransmitting layer 10 with observing from the side to be irradiated withthe laser beam “LB” can be manufactured. Further, information can berecorded on the concave section, so that a reproduced signal, which ishigh in output and quality, can be obtained, and recording andreproducing in less error rate and in high density can be realized.Furthermore, since wobbling period and phase of both sides of theconcave section are equal to each other, interference never happens andaccurate address information can be reproduced.

The case that the energy ray sensitive film 2 is the positive type isexplained above. However, a case of a negative type can also be realizedas same as the positive type.

With referring to FIGS. 14 and 15, a case of negative type energy raysensitive film 2 is explained next.

(Process for Producing Negative Type Plating Die)

FIG. 14 is a cross sectional view of a negative type energy raysensitive film in a producing process of a plated die in a negative typeaccording to the embodiment of the present invention.

In a case of negative type, a concave shaped section and a convex shapedsection are reversely arranged in comparison with those of the positivetype if the same processes for the positive type are applied to thenegative type. Consequently, a relationship between groove and land isalso reversed.

As shown in FIG. 14, a third plating die 12 having a fifth microscopicpattern 3D, which is reversely arranged in comparison with the secondmicroscopic pattern 3A that is formed on the first plating die 5 shownin FIG. 5, is produced through the similar processes of the “process forpreparing substrate” through the “process for producing first platingdie” shown in FIGS. 1 through 5 respectively.

(Process for Forming Negative Type Substrate)

FIG. 15 is a cross sectional view of a negative type substrate in aforming process of negative type substrate according to the embodimentof the present invention.

As shown in FIG. 15, a sixth microscopic pattern 3E is formed bytransferring the fifth microscopic pattern 3D of the third plating die12 to a substrate 8, wherein the third plating die 12 is identical tothe second plating die 7 shown in FIG. 7.

By using the substrate 8, an information recording medium 11 shown inFIG. 10 is manufactured by similar processes to the “process for formingrecording layer” and the “process for forming light transmitting layer”shown in FIGS. 9 and 10 respectively.

In a case that a negative type energy ray sensitive film 2 is used, eachperiod and phase of wobbles of both sides of a convex shaped section,which projects to the light transmitting layer 10 with observing from aside that is irradiated with a laser beam “LB” shown in FIG. 10, can beequalized by the same processes for the positive type energy raysensitive film 2 although the “process for forming second plating layer”and the “process for producing second plating die”, which are shown inFIGS. 6 and 7 respectively, are omitted.

As a result, an information recording medium 11 in which an informationtrack is equivalent to a concave section that projects into the lighttransmitting layer 10 with observing from the side to be irradiated withthe laser beam “LB” can be manufactured. Further, information can berecorded on the concave section, so that a reproduced signal, which ishigh in output and quality, can be obtained, and recording andreproducing in less error rate and in high density can be realized.Furthermore, since each wobbling period and phase of both sides of theconcave section are equal to each other, interference never happens andaccurate address information can be reproduced.

With referring to FIGS. 16 through 18, a supplemental explanation isgiven to features of physical shape of microscopic pattern in theinformation recording medium 11.

FIG. 16 is a fragmentary plan view, partially enlarged, of a microscopicpattern formed on an information recording medium, which is manufacturedby the manufacturing method of information recording medium according tothe embodiment of the present invention.

FIG. 17 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV (ContinuousLinear Velocity) recording in a disc shape, according to the presentinvention.

FIG. 18 is a fragmentary plan view, partially enlarged, of aninformation recording medium, which is suitable for a CLV recording in adisc shape and recorded by a user, according to the present invention.

The information recording medium 11 is recorded by the constant linearvelocity (CLV) method as an information recording medium in disciform.FIG. 16 shows an exemplary configuration, which is composed of threegrooves “G1” through “G3” (hereinafter generically referred to as groove“G”) and two lands “L1” and “L2” (hereinafter generically referred to asland “L”). In FIG. 16, each sidewall of each land “L”, which facestoward an inner circumference direction, is defined as “L1 i”, “L2 i”(hereinafter generically referred to as inner sidewall “Li”)respectively and each sidewall toward an outer circumference directionof each land “L” is defined as “L1 o” and “L2 o” (hereinaftergenerically referred to as outer sidewall “Lo”) respectively. Further,each sidewall of each groove “G”, which faces toward the innercircumference direction, is defined as “G2 i” an “G3 i” (hereinaftergenerically referred to as inner sidewall “Gi”) and each sidewall towardthe outer circumference direction of the groove “G” is defined as “G1 o”and “G2 o” (hereinafter generically referred to as outer sidewall “Go”)respectively, wherein the inner sidewall “Li” and the outer sidewall“Go”, and the outer sidewall “Lo” and the inner sidewall “Gi” are thesame sidewall respectively.

Furthermore, the groove “G” is wobbled in the radial direction andrecorded with an address. The information recording medium 11 ismanufactured by the “process for forming first plating layer” throughthe “process for producing second plating die” shown in FIGS. 4 through7 respectively. Therefore, wobbles of both sidewalls of the groove “G”(that is, “Gi” and Go”) are formed in a same period and phase.Consequently, the sidewalls of the groove “G”, that is, inner sidewall“Gi” and the outer sidewall “Go” are always formed in parallel to eachother.

In FIG. 16, the information recording medium 11 is recorded by the CLVmethod. However, it can be recorded by the constant angular velocity(CAV) method. In the case of the CAV method, both sidewalls of the land“L” (that is, “Li” and “Lo”) are formed in parallel to each other aswell as forming both sidewalls of the groove “G” (that is, “Gi” and“Go”) in parallel to each other.

FIG. 17 shows an exemplary configuration, which is composed of fourgrooves “G1” through “G4” (hereinafter generically referred to as groove“G”) and three lands “L1” through “L3” (hereinafter generically referredto as land “L”). The groove “G” is wobbled in the radial direction andrecorded with an address. In FIG. 17, a centerline of the groove “G” isshown by a chain line. A distance between two chain lines, which areadjacent to each other, is defined as pitch “P”. Wobbling width of thewobbling groove “G” is shown by two doted lines and the width in peak topeak is defined as Δ. In a case of reproducing the information recordingmedium 11, as mentioned above, a laser beam is focused on the groove“G”. A reproducing spot diameter (=λ/NA) of the laser beam is shown as“S” in FIG. 17, (wherein λ is a wavelength of the laser beam forreproducing that is installed in a reproducing apparatus and NA isnumerical aperture of an objective lens for converging the laser beam).

The dimensions of the fourth microscopic pattern 3C is defined as P≦S.As shown in FIG. 18, by recording only in a portion of the recordinglayer 9 that is equivalent to the groove “G”, a record mark “M”, whichis in high output and less fluctuation in the time axis, can be written.Further, when reproducing the information recording medium 11, a recordmark “M”, which is hardly erased by a reproducing laser beam, can berecorded. By decreasing the pitch “P” in dimensions so as to be smallerthan the reproducing spot diameter “S” of the laser beam,heat-accumulating effect is generated and recording in high energydensity, that is, in high contrast can be realized.

If a violaceous laser, for example, is used, λ (wavelength) of theviolaceous laser is within a range of 350 nm to 450 nm. Further, if anobjective lens in high NA is used, NA is within a range of 0.75 to 0.9.Consequently, a pitch “P” is assigned to be within a range of 250 nm to600 nm. Furthermore, in a case of taking into consideration of recordinga digital video picture by a high definition television (HDTV) forapproximately two hours, more than 20 GB of recording capacity isessential. Therefore, a pitch “P” is desirable to be within a range of250 nm to 450 nm. In a case that NA is within a range of 0.85 to 0.9,the pitch “P” is desirable to be within a range of 250 nm to 400 nmparticularly. In a case that NA is 0.85 to 0.9 and λ is within a rangeof 350 nm to 410 nm, the pitch “P” is most desirable to be within arange of 250 nm to 360 nm.

More, with respect to depth of the fourth microscopic pattern 3C, thatis, elevation difference between a concave shaped section and a convexshaped section, it is suitable for the elevation difference to be withina range of λ/8n to λ/20n, wherein “n” is a refractive index of the lighttransmitting layer 11 at the wavelength of λ.

Reflectivity of the recording layer 9 reduces in response to thepresence of the fourth microscopic pattern 3C, so that the elevationdifference is desirable to be smaller. A limit of the elevationdifference that prevents an error rate of reproduced signal fromdeteriorating is preferable to be less than λ/10n. Further, a push-pullsignal (difference signal) increases together with increasing of theelevation difference while tracking, so that more than λ/18n ofelevation difference is essential as a limit value of enabling thetracking. In other words, the elevation difference is most desirable tobe within a range of λ/10n to λ/18n.

In a case that the fourth microscopic pattern 3C is designed so as to beP≦S, it is essential for the wobbling width Δ to be assigned as Δ<P. Ifthe fourth microscopic pattern 3C is formed as mentioned above, both ofadjoining tracks (for example, both of adjoining grooves “G”) would notcontact with each other physically, so that cross writing can be avoidedwhen recording.

The inventors of the present invention actually make an experiment thata phase change recording material is selected for a recording layer 9 ofinformation recording medium 11 and the recording layer 9 is recorded inaccordance with reflectivity difference, phase difference or bothdifferences of the reflectivity and the phase.

In other words, by writing random data in the information recordingmedium 11 by the phase change recording method and reproducing anaddress by the push-pull method, it is found that a limit, which enablesto detect an address, is 0.01 S≦Δ and the random data that is written bythe phase change recording method is extremely superimposed on theaddress as noise with respect to a groove, which is manufactured by Δthat is smaller than 0.01 S, and resulted in increasing of an error rateof the address rapidly.

In the case of 0.01 S≦Δ, an address can be reproduced sufficiently eventhough the recording layer 9 is in a low reflectivity state (such as anamorphous state) by the phase change recording method. In the case of0.15 S<Δ, fluctuation in the time axis of an address occurs because ofinfluence of reproduction cross-talk from an adjoining track andresulted in deteriorating stability. Accordingly, a condition, whichsatisfies relation of Δ<P and 0.01 S≦Δ≦0.15 S, is most suitable for therecording layer 9.

In FIG. 18, a record mark “M” is recorded only in a wobbling groove “G”.The record mark “M” shows a modulation signal that is ON or OFF and isin various length. As mentioned above, the record mark “M” is formed inthe recording layer 9. In a case that the recording layer 9 is made by aphase change material, the record mark “M” is recorded in the recordinglayer 9 by reflectivity difference, phase difference or both differencesof the reflectivity and the phase.

With respect to a recording method of the record mark “M”, the CLVrecording method is applied for the record mark “M” to be recorded by auser if the fourth microscopic pattern 3C of the information recordingmedium 11 is manufactured for the purpose of the CLV recording. On thecontrary, if the fourth microscopic pattern 3C of the informationrecording medium 11 is manufactured for the CAV recording, the CAVrecording method is applied for the record mark “M” to be recorded by auser. Consequently, user data that is in synchronism with an address canbe accurately recorded while reproducing accurate address informationfrom a groove “G”.

With referring to FIGS. 19 through 27, the amplitude-shift keyingmodulation wave 250 (250, 251 and 252), the frequency-shift keyingmodulation wave 260 (260, 261 and 262) and the phase-shift keyingmodulation wave 270 (270, 271 and 272), which are used for recording anaddress in an information recording medium 11, are explained next.

As mentioned above, these modulated waves are a signal form to beinputted to the beam shaper 122, at the same time, they are identical toa groove shape to be formed in a first microscopic pattern 3.

That is, the time axis direction of these modulated waves aretransformed into a track direction of groove “G” in the firstmicroscopic pattern 3, at the same time, an amplitude direction ofmodulation signal is transformed into a direction perpendicular to thegroove “G” and the modulation signal is recorded in the groove “G”.

In other words, the time axis direction of these modulated waves aretransformed into a track direction of groove “G” in a forth microscopicpattern 3C, at the same time, an amplitude direction of modulationsignal is transformed into a direction perpendicular to the groove “G”and the modulation signal is recorded in the groove “G”. Hereinafter,the modulated waves are explained as a shape of the groove “G” thatconstitutes the fourth microscopic pattern 3C. They are the samesituation as a signal form to be inputted to the beam shaper 122.

With referring to FIGS. 19 through 21, the amplitude-shift keyingmodulation waves 250, 251 and 252 are depicted.

As shown in FIG. 19, the amplitude-shift keying modulation wave 250 isrecording data in shape by the amplitude-shift keying modulation system.Actually, the amplitude-shift keying modulation wave 250 is constitutedby an amplitude section 2501 and a non-amplitude section 2500, whereinthe amplitude section 2501 is formed by wobbling a groove “G” in apredetermined period.

In other words, the amplitude section 2501 is a wobbling part of thegroove “G” and the non-amplitude section 2500 is a non-wobbling part ofthe groove “G”. Further, the amplitude section 2501 and thenon-amplitude section 2500 are corresponding to “1” and “0” of a databit respectively.

The amplitude section 2501 is composed of a plurality of waves. A numberof waves is not limited. However, if it is too many, length of thenon-amplitude section 2500 consequently becomes longer and resulted inthat a fundamental wave, which produces a gate when reproducing, ishardly detected. Therefore, two to one hundred waves, preferably threeto thirty waves are suitable for the number of waves of the amplitudesection 2501. As mentioned above, digital data (in a case of FIG. 19, itis “10110”) is recorded by whether amplitude is existed or not, orwhether amplitude strength exceeds a predetermined value or not.

A push-pull method, which will be explained later, can be used forreading out recorded data. Further, it should be understood that theamplitude-shift keying modulation wave 250 does not limit each length oreach amplitude size of the amplitude section 2501 and the non-amplitudesection 2500 to specific figure. In the case of the amplitude-shiftkeying modulation wave 250 shown in FIG. 19, the length of the amplitudesection 2501 is set to be longer than that of the non-amplitude section2500.

In FIG. 20, an amplitude-shift keying modulation wave 251 is constitutedby amplitude sections 2511 a through 2511 c and non-amplitude sections2511. Each amplitude of the amplitude sections 2511 a through 2511 c isunequal to each other. However, unequal amplitude is acceptable for theamplitude-shift keying modulation system. Further, it is also acceptablethat assigning each amplitude in multiple levels intentionally realizesrecording in multi-values more than three values.

Furthermore, in a case of an amplitude-shift keying modulation wave 252shown in FIG. 21, each amplitude of amplitude sections 2521 is equal toeach other and each length of the amplitude sections 2521 is equal tothat of non-amplitude sections 2520. This configuration is alsoacceptable for the amplitude-shift keying modulation system.

Particularly, in a case that data are recorded in digital by the binaryvalue of “0” and “1”, an isotropic layout as shown in FIG. 21 isdesirable for the digital recording by the binary value. In other words,if each height of the amplitude sections 2521 is made equal to eachother and each length of the amplitude sections 2521 is made equal tothat of the non-amplitude sections 2520, judging “0” or “1” whenreproducing can be realized by sufficient threshold value of amplitude.Moreover, data arranged in series can be read out by one thresholdvalue, so that a reproducing circuit can be simplified.

Even in a case where jitter exists in reproduced data, the influence ofthe jitter can be minimized. Further, with assuming that a code to berecorded is ideally symmetrical, total length of the amplitude sections2521 is made equal to that of the non-amplitude sections 2520 andresulted in no DC (direct current) component in a reproduced signal. Itis advantageous to digital recording that no DC component releases aburden on data decoding and servo.

As mentioned above, by using any of the amplitude-shift keyingmodulation waves 250, 251 and 252, an address is recorded in aninformation recording medium 11 according to the embodiment of thepresent invention. Either “0” or “1” is recorded in response to whethera wobble is existed on a sidewall of groove “G” or not, so that abilityof judging “0” or “1” is excellent. In other words, a low error rate canbe obtained even though an address is in relatively low C/N (carrier tonoise ratio). Further, influence of random noise caused by the recordingcan be reduced and a low error rate can be maintained, even thoughrecording on a recording layer 9 is performed by a user.

With referring to FIGS. 22 through 24, frequency-shift keying modulationwaves 260 through 262 are explained next.

The frequency-shift keying modulation waves 260 through 262 are awaveform for recording data in shape by the frequency-shift keyingmodulation system and the waveform is composed of a plurality ofsections, which are formed by wobbling a groove “G” by variousfrequencies. Actually, in the case of binary data, the frequency-shiftkeying modulation wave is recorded in shape by using a higher frequencysection and a lower frequency section. In a case of multi-valued datasuch as “n” values, a frequency-shift keying modulation wave is recordedin shape by the frequency-shift keying modulation system that uses “n”kinds of frequency sections.

FIG. 22 is one example of recording data “10110” in shape. In FIG. 22,the frequency-shift keying modulation wave 260 is composed of threehigher frequency sections 2601 and two lower frequency sections 2600.The higher frequency section 2601 and the lower frequency section 2600are equivalent to “1” and “0” of a data bit respectively and they arerecorded in digital by changing the frequency at each one channel bit.

A number of waves that constitute each frequency section is not limitedto one specific number. Each frequency section is composed of a wavethat continues more than one cycle. However, in consideration of thatdata are not redundant too much in a reproducing apparatus so as todetect a frequency accurately and obtain a certain degree of datatransfer rate, each frequency section, which is corresponding to eachdata bit that is mentioned above, is desirable to be constituted by anumber of waves within a range of one cycle to one hundred cycles,preferably one cycle to thirty cycles.

It is acceptable that each amplitude of the higher frequency section2601 and the lower frequency section 2600 is equal to each other.However, an amplitude ratio is not limited to one specific figure.Amplitude of the higher frequency section 2601 can be formed larger thanthat of the lower frequency section 2600 in consideration of a frequencyresponse of reproducing apparatus. If the higher frequency section 2601is formed in larger amplitude, output attenuation at a higher frequencyrange in the reproducing apparatus can be complemented and resulted inimprovement of readout ability of the reproducing apparatus. Inaddition, the commonly known push-pull method can be used for readingout recorded data.

It should be understood that the information recording medium 11according to the present invention does not place a restraint onphysical length or amplitude size of a channel bit, which is composed ofthe higher frequency section 2601 and the lower frequency section 2600.For example, in FIG. 22, the physical length of lower frequency section2600 is designated to be longer than that of the higher frequencysection 2601.

As shown in FIG. 23, it is acceptable for a frequency-shift keyingmodulation wave 261 that each amplitude and each length of a higherfrequency section 2611 and a lower frequency section 2610 are equivalentto each other.

By equalizing each amplitude and length as mentioned above, judging “0”or “1” can be performed by sufficient threshold value of amplitude whenreproducing. Further, data arranged in series can be read out by onethreshold value of time, so that a reproducing circuit can besimplified. Furthermore, in case jitter exists in reproduced data, theinfluence of the jitter can be minimized. Moreover, with assuming that acode to be recorded is ideally symmetrical, total length of the higherfrequency sections 2611 is equal to that of the lower frequency sections2610 and resulted in no DC component in a reproduced signal. It isadvantageous to digital recording that no DC component releases a burdenon data decoding and servo.

In FIGS. 22 and 23, the higher frequency section 2601 or 2611 and thelower frequency section 2600 or 2610 are connected to each otherrespectively, wherein each waveform rises at a point where a channel bitchanges. However, phase jump happens in probability of 50% at the momentwhen a channel bit changes. Consequently, a high frequency component isgenerated and resulted in deterioration of power efficiency per eachfrequency.

FIG. 24 shows an example for improving the above-mentioned problem. InFIG. 24, a higher frequency section 2621 r or 2621 f (hereinafterreferred generically to as higher frequency section 2621) and a lowerfrequency section 2620 are arranged so as to maintain phase continuityat a point where each channel bit of a frequency-shift keying modulationwave 262 changes over. Actually, a starting phase of the lower frequencysection 2620 is selected so as to be that a phase direction of the endof the higher frequency section 2621 and a phase direction of the startof the lower frequency section 2620 are the same direction. Further, thereverse connection is the same as such that a starting phase of thehigher frequency section 2621 is selected so as to be that a phasedirection of the end of the lower frequency section 2620 and a phasedirection of the start of the higher frequency section 2621 are the samedirection.

If the starting phase is selected as mentioned above, continuity ofphase is maintained and power efficiency is improved. Further, areproduction envelope becomes constant, so that a data error rate ofaddress, which is recorded in the information recording medium 11, isimproved.

Furthermore, a frequency of the higher frequency section 2621 (2601,2611 or 2621) and the lower frequency section 2620 (2600, 2610 or 2620)can be arbitrary selected. However, in order to eliminate interferencewith a frequency range that is provided for recording data on theinformation recording medium 11 by a user, it is strictly required forthe higher frequency section 2621 not to be extremely high frequency incomparison with the frequency of lower frequency section 2620.

On the other hand, in order to improve a reproduction error rate ofaddress data, frequency difference between the higher frequency section2621 and the lower frequency section 2620 shall be kept in certaindegree so as to maintain excellent separativeness. From these points, afrequency ratio of the higher frequency section 2621 to the lowerfrequency section 2620 is desirable to be within a range of 1.05 to 5.0,particularly, within a range of 1.09 to 1.67. In other words, phaserelation between two frequencies is desirable to be within a range of2π±(π/20.5) to 2π±(π/0.75), particularly, within a range of 2π±(π/12) to2π±(π/2) (that is, 360±15 degrees to 360±90 degrees), wherein thereference phase is defined as 2π.

With respect to a frequency ratio (ratio of higher frequency to lowerfrequency), if the frequency ratio shown in FIG. 24 is assigned to be1.5, there exists a phase relation between these higher and lowerfrequencies such that the higher frequency is shifted by −π/2.5 from areference phase of a single-frequency wave and the lower frequency isshifted by +π/2.5 from the reference phase of the single-frequency wave,wherein the phase relation becomes 2π±(π/2.5) when the reference phaseis defined as 2π. In other words, the phase relation is 360±72 degrees.It is expressed that these two frequencies are integral multiple(wherein it is three times and two times respectively) of the frequency(in this case 0.5) of the single-frequency wave. In addition thereto,the single-frequency wave is a wave having a frequency that is integralmultiple of a frequency of fundamental wave accurately.

Consequently, it is advantageous for a demodulation circuit to besimplified. Further, generating a clock signal becomes easier by using acircuit having a window of 0.5. Furthermore, demodulation can beperformed by a synchronous detector circuit. In this case, an error ratecan be reduced extremely.

As mentioned above, an address is recorded in the information recordingmedium 11 of the present invention by the frequency-shift keyingmodulation waves 260, 261 and 262. The binary data “0” or “1” isrecorded in accordance with change of a wobbling frequency, so thatability of judging “0” or “1” is excellent. In other words, an addresscan be obtained in a low error rate even though a C/N is relatively low.

More, influence of random noise caused by the recording can be reducedand a low error rate can be maintained, even though the recording layer9 of the information recording medium 11 is recorded by a user.

Moreover, combining a frequency and a period can exhibit data. If eachwobbling frequency of higher and lower frequencies is defined so as tobe (higher frequency)÷(period of the higher frequency)=(lowfrequency)÷(period of lower frequency) although it is not shown in anydrawings, each phase of wobbles coincides with each other when changingover the wobbling frequency, and a shape of groove “G” can be displacedsmoothly at a point where a wobbling frequency changes over.

Accordingly, an error when detecting a wobble during reproductiondecreases and resulted in an effect that reduces a demodulation error ofinformation, which is embedded in a wobble. In a case of recordinginformation “0” for eight periods by a wobble of 150 kHz and recordinginformation “1” for seven periods by a wobble of 131.25 kHz, forexample, each phase of 150 kHz and 131.25 kHz coincides with each otherat a point where the frequency of 150 kHz changes over to 131.25 kHz orvise versa. Therefore, excellent information can be recorded.

With referring to FIGS. 25 through 27, phase-shift keying modulationwaves 270, 271 and 272 are explained next.

As shown in FIG. 25, the phase-shift keying modulation wave 270 isformed by recording data in shape by the phase-shift keying modulationsystem and composed of a plurality of sections, which are formed bywobbling a groove “G” by a predetermined frequency. In the case ofbinary data, the phase-shift keying modulation wave 270 is composed ofan advancing phase section 2701 and a receding phase section 2700. In acase of multi-valued data such as “n” values, a phase-shift keyingmodulation wave is composed of “n” phase sections, which correspond to“n” kinds of phases respectively.

FIG. 25 is one example of recording data “10110” in shape. In FIG. 25,the phase-shift keying modulation wave 270 is composed of threeadvancing phase sections 2701 and two receding phase sections 2700. Theadvancing phase section 2701 and the receding phase section 2700 areequivalent to “1” and “0” of a data bit respectively and recorded indigital by changing the phase at each one channel bit.

Actually, the advancing phase section 2701 and the receding phasesection 2700 are exhibited by a sinusoidal wave of “sin 0” and anothersinusoidal wave of “sin(−π)” respectively. As shown in FIG. 25, theadvancing phase section 2701 and the receding phase section 2700 areconstituted by one cycle of waveform respectively. However, phasedifference between them is as many as π, so that they can be separatedand reproduced sufficiently by the envelope detection method and thesynchronous detection method.

Each frequency of the advancing phase section 2701 and the recedingphase section 2700 is identical to each other. A number of waves, whichconstitutes the advancing phase section 2701 and the receding phasesection 2700, is not restricted to a specific number. Both phasesections are composed of a wave that continues more than one cycle.However, in consideration of that data are not redundant too much in areproducing apparatus so as to detect a frequency accurately and obtaina certain degree of data transfer rate, each phase section, which iscorresponding to each data bit that is mentioned above, is desirable tobe constituted by a number of waves within a range of one cycle to onehundred cycles, preferably one cycle to thirty cycles.

It is acceptable for each physical length of the advancing phase section2701 and the receding phase section 2700 to be identical or not. If eachphysical length is identical, data, which are combined in series, can bedivided into piece by a predetermined time (clock) when reproducing, sothat a reproduction circuit can be simplified. Further, in case jitterexists in reproduced data, the influence of the jitter can be minimized.

It is also acceptable for each amplitude of the advancing phase section2701 and the receding phase section 2700 to be coincide with each otheror not. However, in consideration of easier reproduction, it isdesirable for the advancing phase section 2701 and the receding phasesection 2700 that each amplitude of them coincides with each other.

The information recording medium 11 of the present invention can dealwith not only binary data but also multi-valued data. Dealing with howmany kinds of phases depends on that phase difference of each data bitcan be separated into what degree of resolution. The limit of separationof the information recording medium 11 is obtained experimentally by theinventors of the present invention and it is confirmed that phasedifference can be separated into up to π/8. In other words, amulti-valued channel bit or various phase sections, which constitute themulti-valued channel bit, can deal with minimum phase difference of eachphase sections within a range of π/8 to π, (wherein π is equivalent tominimum phase difference of a binary data). That is, a wide range ofdata from binary to hexadecimal can be dealt with.

FIG. 26 is an example showing a phase-shift keying modulation wave 271that is recorded with 4-valued data. In FIG. 26 the phase-shift keyingmodulation wave 271 is composed of a first phase section 2710 [sin(−3π/4)], a second phase section 2711 [sin (−π/4)], a third phasesection 2712 [sin (π/4)] and a fourth phase section 2713 [sin (3π/4)].Minimum phase difference of each phase section is π/2, so that each ofthe 4-valued data can be sufficiently separated and obtained. In FIG.26, the first phase section 2710, the second phase section 2711, thethird phase section 2712 and the fourth phase section 2713 arecorresponded to data “1”, “2”, “3” and “4” respectively for convenience.

When recording multi-valued data such as mentioned above, themulti-valued data can be replaced by multidimensional data. Withassuming that the data is two-dimensional data (x, y), for example, itis applicable for the data “1” through “4” that the data “1” is replacedby data (0, 0), the data “2” by data (0, 1), the data “3” by data (1, 0)and the data “4” by data (1, 1) respectively.

FIG. 27 is another example, which deals with an address in theinformation recording medium 11 of the present invention. In FIG. 27, afundamental wave is a saw-tooth wave and the waveform is asymmetricalfor rising and falling sections. By controlling the rising and fallingsections individually, difference of phase is exhibited.

In FIG. 27, data “1” is recorded as a section 2721 of which a wave risesgradually and falls rapidly (hereinafter referred to as a rapidlyfalling section 2721), and data “0” as a section 2720, which risesrapidly and falls gradually (hereinafter referred to as a rapidly risingsection 2720).

When address data “10110” is recorded, for example, as shown in FIG. 27,the rapidly falling section 2710, the rapidly rising section 2720, therapidly falling section 2721, the rapidly falling section 2721 and therapidly rising section 2720 are sequentially recorded in shape. Such arecording method that records data by difference between a rising angleand a falling angle is advantageous for the data to be demodulated byinputting the data into a high-pass filter and extracting a differentialcomponent. Further, it is also advantage of the recording method thatthe data can be reproduced even under low C/N condition.

As mentioned above, an address is recorded in the information recordingmedium 11 of the present invention by the phase-shift keying modulationwaves 270, 271 and 272. The binary data “0” or “1” is recorded inaccordance with phase change of a number of wobbles, so that ability ofjudging “0” or “1” is excellent. Particularly, a frequency of thephase-shift keying modulation system is constant. Therefore, a filter,which is installed in a preceding stage of an address demodulationcircuit, can be assigned to be a band-pass filter, which is specializedin one frequency, and any kind of noises including a noise that iscaused by recording by a user can be eliminated effectively.

In other words, a lower error rate can be obtained even though a C/N isrelatively low. Further, influence of random noise caused by therecording can be effectively eliminated and a low error rate can bemaintained, even though the recording layer 9 of the informationrecording medium 11 is recorded by a user.

As mentioned above, when reproducing the information recording medium 11that is recorded with those modulated waves, a reproducing apparatusthat is equipped with a commonly known 2-division or 4-division photodetector can be used. In a case that the information recording medium11, which is loaded in the reproducing apparatus, is disciform, a signalis outputted by obtaining difference between an output from a divisionalsegment of the photo detector that is allocated in an innercircumference side of the information recording medium 11 and anotheroutput from another divisional segment that is allocated in an outercircumference side of the information recording medium 11 (this methodis referred to as “push-pull method”).

The output generates a signal that corresponds to a shape of wobblinggroove “G”. Therefore, the amplitude-shift keying modulation waves 250,251 and 252, the frequency-shift keying modulation waves 260, 261 and262 or the phase-shift keying modulation waves 270, 271 and 272, whichare a shape of constituting the information recording medium 11, arerestored as an electric signal. In other words, a track direction ofgroove “G” is transformed into a time axis direction of reproducedsignal and a right angle direction that is perpendicular to the trackdirection of the groove “G” is transformed into an amplitude directionof the reproduced signal. The electric signal is the same signal as thatis inputted into the beam shaper 122, which is used while manufacturingthe information recording medium 11. Consequently, the inputted signalis restored as an almost similar signal to the inputted signal.

In the above-mentioned descriptions that are explained with referring toFIGS. 19 through 27, it is explained as one example of recording afundamental wave, which is defined as a sine wave. Further, recording afundamental wave, which is defined as a cosine wave, is also acceptable.An address wobble can be used by selecting out from the above-mentionedvarious kinds of modulated waves and can be selected in accordance withan application of the information recording medium 11.

It is acceptable that two or three different modulated waves areselected out from the various kinds of modulated waves mentioned aboveand recorded in different areas of a groove “G” respectively by thetime-division recording method as well as forming the groove “G” by onemodulated wave that is selected out from the various kinds of modulatedwaves. Further, it is acceptable that two different modulation systemsare selected and modulated waves that are modulated by each of the twomodulation systems are recorded by superimposing them in a same area ofthe groove “G” as multiplex recording.

Furthermore, it is applicable that a single frequency wave is recordedby superimposing it on each of the modulated waves. In other words, afrequency that is a same frequency as or different frequency to afrequency, which constitutes the amplitude-shift keying modulation waves250, 251 and 252, and the frequency-shift keying modulation waves 260,261 and 262, can be recorded by superimposing the same frequency or thedifferent frequency on them.

Particularly, with respect to the frequency-shift keying modulation wave260, either frequency of higher frequency section or lower frequencysection can be superimposed on the frequency-shift keying modulationwave 260. Similarly, integer multiples of either frequency of higherfrequency section or lower frequency section or the frequency over aninteger can be superimposed on the frequency-shift keying modulationwave 260.

With respect to the phase-shift keying modulation wave 270, integermultiples of a frequency, which constitutes the phase-shift keyingmodulation wave 270, or the frequency over an integer can besuperimposed on the phase-shift keying modulation wave 270.

In any cases, the single frequency wave, the amplitude-shift keyingmodulation wave 250, the frequency-shift keying modulation wave 260 andthe phase-shift keying modulation wave 270 can be separated from thesuperimposed wave by a reproducing apparatus that is equipped withcommonly known band-pass filter, phase detector or like. According to anexperiment in the phase-shift keying modulation wave 270, for example,the phase-shift keying modulation wave 270 and a single frequency can beseparated and reproduced without any problem if an amplitude ratio ofthe phase-shift keying modulation wave 270 to the single frequency waveis within a predetermined range of 1:5 to 5:1 when recording the singlefrequency wave by superimposing.

With respect to an alternative method, a type of wobble waveform can beused as information. For example, it is possible that information of awobble, which is formed by a sine wave, is defined as “0” andinformation of another wobble, which is formed by a saw-tooth wave or atriangular wave, is defined as “1”. Further, it is also possible todefine as that information of a first wobble, which is formed by a sinewave, is “0”, information of a second wobble, which is formed by arectangular wave is “1”, information of a third wobble, which is formedby a rapidly rising saw-tooth wave, is “2”, information of a fourthwobble, which is formed by a rapidly falling saw-tooth wave, is “3”,information of a fifth wobble, which is formed by triangular wave, is“4” and information of a section, which is formed by a straight linewithout wobbling, is “5”. In a case of detecting even a shape of wobbleby a reproducing apparatus, information can be exhibited by the quinarynumber system and resulted in advancing address information to higherdensity.

As mentioned above, the embodiment of the present invention explainsabout only fundamental areas. However, it should be understood thatvarious modifications and additional functions could be applied to theinformation recording medium of the present invention in accordance withapplications.

In the above-mentioned embodiment, each constituting component can bereplace by each other and exchanged by another component that isdisclosed in the specification. For example, the shape of theinformation recording medium 11 is not restricted to one shape, anyshape such as disc, card and tape can be applied for the informationrecording medium 11. Further, a shape in circular, rectangular orelliptic can also be acceptable. Furthermore, an information recordingmedium having a hole is also acceptable.

In a case that the information recording medium 11 is in disciform, itsdimension is not limited to one dimension. For example, in the case ofdiameter, various diameters from 20 mm to 400 mm can be applied for theinformation recording medium 11. Any diameter such as 30, 32, 35, 41,51, 60, 65, 80, 88, 120, 130, 200, 300 and 356 mm can be acceptable.

It is also acceptable to laminate two information recording mediums 11together by making each substrate 8 of the information recording mediums11 face each other. Further, it is acceptable to layer one set of arecording layer 9 and a light transmitting layer 10 over a lighttransmitting layer 10 of the information recording medium 11.Consequently, recording capacity of the information recording medium 11can be increased approximately twice. Furthermore, it is also acceptableto form a multi-layered information recording medium by layering aplurality of sets of a recording layer 9 and a light transmitting layer10.

A groove “G” or a land “L” can be formed by not only the CLV method andthe CAV method but also the ZCAV (Zone Constant Angular Velocity) andZCLV (Zone Constant Linear Velocity) methods that are a method offorming zones, which are different from each other in radius, whereineach zone differs in a controlling system. In a case of forming a groove“G” or a land “L” by the ZCAV method, for example, CLV is realized ineach zone and an information recording medium 11 (or a flat substrate 1)is totally controlled by a velocity that is close to CAV. On thecontrary, in a case of the ZCLV method, CAV is realized in each zone andan information recording medium 11 is totally controlled by a velocitythat is close to CLV.

Further, in the first through sixth microscopic patterns 3, 3A, 3B, 3C,3D and 3E, a groove “G” and a land “L” are designated to be flatrespectively. However, they are not limited to flat. At least either oneof groove “G” and land “L” can be formed in a V-letter shape or anA-letter shape in their cross sectional view.

The recording layer 9 is shown as a single layer in FIGS. 9 and 10.However, the recording layer 9 can be formed by a plurality of thin filmmaterials for a purpose of improving recording and reproducingcharacteristics and storage stability. With respect to an auxiliarymaterial for such a thin film material, alloys composed of an elementsuch as silicon, tantalum, zinc, magnesium, calcium, aluminum, chromiumand zirconium, (wherein an alloy includes a compound such as oxide,nitride, carbide, sulfide and fluoride), and a high reflective film(heat-sink material such as aluminum, gold and silver, and variousalloys that include at lest one of them) can be layered in addition to amajor material. Particularly, in a case that the recording layer 9 isformed by a phase change material, by laminating a dielectric materialsuch as ZnS, SiO, SiN, SiC, AlO, AlN, MgF and ZrO on the above-mentionedrecording material, reflectivity can be optimized, reproduction luminousenergy can be increased. Further, a number of rewriting frequency,reproducing characteristic, recording characteristic and storagestability can be improved.

Furthermore, commonly known layers such as an antistatic layer, alubricative layer and a hard coat layer can be formed on the lighttransmitting layer 10 on the opposite side to the recording layer 9although they are not shown in drawings. With respect to an actualmaterial for the antistatic layer, a resin such as energy ray curableresin and thermosetting resin that are dispersed with surface-activeagent and conductive particles can be used. With respect to an actualmaterial for the lubricative layer, liquid lubricant of which surfaceenergy is adjusted by modifying hydrocarbon macromolecule with siliconand fluorine can be used. Thickness of the lubricative layer isdesirable to be within a range of 0.1 nm to 10 nm approximately. More,with respect to an actual material for the hard coat layer, a resin,which transmits more than 70% of light having wavelength λ, such asthermosetting resins, various energy ray curable resins (includingexamples of UV ray curable resins, visible radiation curable resins andelectron beam curable resins), moisture curable resin, plural liquidmixture curable resin and thermoplastic resin containing solvent can beused.

The hard coat layer is desirable to exceed a certain value of the“scratch test by pencil” regulated by the Japanese Industrial Standard(JIS) K5400 in consideration of abrasion resistance of the lighttransmitting layer 10. In consideration of that a hardest material ofthe objective lens is glass, a value of the “scratch test by pencil” forthe hard coat layer is most preferable to be more than the “H” grade. Ifthe test value is less than the “H” grade, dust that is caused byscraping the hard coat layer is remarkably generated. Consequently, anerror rate is deteriorated abruptly. Thickness of the hard coat layer isdesirable to be more than 0.001 mm in consideration of shock resistance,more desirable to be less than 0.01 mm in consideration of warp of antotal information recording medium 10. With respect to other materialsfor the hard coat layer, an element, which transmits more than 70% oflight having a wavelength λ and has a value of the “scratch test bypencil” of more than the “H” grade, such as carbon, molybdenum andsilicon, and their alloy (including composition such as oxide, nitride,sulfide, fluoride and carbide) can be used (its film thickness is withina range of 1 nm to 1000 nm).

A label printing can be applied on the surface of the substrate 8 on theopposite side to the recording layer 9 although the label printing isnot shown in any drawings. Various energy ray curable resins containingpigment and dye (such as UV ray curable resin, visible radiation curableresin and electron beam curable resin) can be used suitably for thelabel printing. Thickness of the label printing is desirable to be morethan 0.001 mm in consideration of visibility of the printing, moredesirable to be less than 0.05 mm in consideration of warp of the totalinformation recording medium 11.

A hologram for identifying the information recording medium 11 and avisible microscopic pattern can be formed in an area other than apredetermined area for recording.

An information recording medium 11 can be installed in a cartridge so asto improve ability of loading the information recording medium 11 into areproducing apparatus and protectiveness of the information recordingmedium 11 while loading.

A record mark “M”, which is recorded on the information recording medium11 by a user, can be recorded by either the mark position recordingmethod or the mark end recording method. A signal, which is used forrecording, is a modulation signal that is a so-called (d, k) code, whichis defined as that a minimum mark length is “d+1” and a maximum marklength is “k+1”, wherein either a fixed length code or a variable lengthcode can be applied for a (d, k) modulation signal. Actually, withdefining that a minimum mark length is 2T, a (d, k) modulation such as(1, 7) modulation, 17PP modulation, DRL modulation, (1, 8) modulationand (1, 9) modulation can be used.

An example representing the (1, 7) modulation of the fixed length codeis the “D1, 7” modulation (that is disclosed in the Japanese PatentApplication No. 2001-80205 in the name of Victor company of Japan,Limited). The “D1, 7” modulation can be replaced by the (1, 7)modulation or the (1, 9) modulation, which is based on the “D4, 6”modulation of the fixed length code (that is disclosed in the JapanesePatent Application Laid-open Publication No. 2000-332613). The 17PPmodulation is one of the (1, 7) modulation of the variable length codeand disclosed in the Japanese Patent Application Laid-open PublicationNo. 11-346154/1999.

With respect to the (2, 7) modulation and the (2, 3) modulation, whichare the variable length code with defining the minimum mark length as3T, the EFM modulation, the EFM plus modulation and the “D8-15”modulation (that is disclosed in the Japanese Patent ApplicationLaid-open Publication No. 2000-286709) can be used. Further, amodulation system, which defines the minimum mark length as 4T (such asthe (3, 17) modulation), and another modulation system, which definesthe minimum mark length as 5T, (such as the (4, 21) modulation) can beused.

With referring to FIGS. 28 and 29, a first reproducing apparatus, whichis used for reproducing an information recording medium 11 of thepresent invention, is explained.

In FIG. 28, a first reproducing apparatus 500 is at least composed of apickup 50 for reading out reflected light from an information recordingmedium 11, a motor 51 for rotating the information recording medium 11,a servo controller 52 for controlling to drive the pickup 50 and themotor 51, a turntable 53 for supporting the information recording medium11 while rotating, a demodulator 54 for demodulating an informationsignal that is read out by the pickup 50, an interface (I/F) 55 foroutputting a signal that is demodulated by the demodulator 54 and acontroller 60 that controls the first reproducing apparatus 500 totally.

The demodulator 54 hereupon is a digital converter that returns 16-bitdata to original 8-bit data if a reproduced signal is modulated by theEFM plus modulation (8-16 modulation) method, which is commonly used forthe DVD system.

The turntable 53 and the information recording medium 11 are connectedwith plugging a center hole Q of the information recording medium 11with the turntable 53. Such a connection between the turntable 53 andthe information recording medium 11 can be either a fixed connection orsemi-fixed connection, which can load or release the informationrecording medium 11 freely. Further, the information recording medium 11can be installed in a cartridge. With respect to a cartridge, a commonlyknown cartridge having an opening and closing mechanism in the centercan be used as it is.

The motor 51 is linked to the turntable 53, supports the informationrecording medium 11 through the turntable 53 and supplies relativemotion for reproduction to the information recording medium 11. A signaloutput can be supplied to a not shown external output terminal ordirectly supplied to a not shown display device, audio equipment orprinting equipment.

The pickup 50 is at least composed of a light emitting element 50 a,which emits light having single wavelength λ within a range of 350 nm to450 nm, desirably 400 nm to 435 nm, an objective lens 50 b havingnumerical aperture NA within a range of 0.75 to 0.9 and a 4-divisionphoto detector 50 c, which receives reflected light that is reflected bythe information recording medium 11 although they are not shown in FIG.28. Furthermore, the pickup 50 forms reproducing light 99 in conjunctionwith these components. It is acceptable that the light emitting element50 a is a semiconductor laser of gallium nitride system compound or alaser having a second harmonic generating element.

According to an actual survey that is made by the inventor of thepresent invention, laser RIN (Relative Intensity Noise) of a secondharmonic generating element is −134 dB/Hz and that of a semiconductorlaser of gallium nitride system compound is −125 dB/Hz. The noise levelof the semiconductor laser of gallium nitride system compound is largerthan that of the second harmonic generating element by 9 dB. However,both of them can be used suitably.

With referring to FIG. 29, the photo detector 50 c is explainedhereupon.

FIG. 29 is a plan view of the photo detector 50 c, which shows adivision state and relative relation with the information recordingmedium 11.

In FIG. 29, the photo detector 50 c is divided into four elements. Inother words, four divided elements A, B, C and D are allocated so as tobe related to the radial direction and the tangential direction of theinformation recording medium 11. Electric currents, which are obtainedfrom each of the elements A, B, C and D when they receive light, are Ia,Ib, Ic and Id respectively. In a case of generating a total sum signal,all currents are summed up to “(Ia+Ib+Ic+Id)”. Further, in a case ofgenerating a differential signal (push-pull signal), by subtracting eachsum in the tangential direction, “(Ia+Ib)−(Ic+Id)” is produced.

The servo controller 52 is indicated just one in FIG. 28. However, itcan be divided into two; one is a driving control servo for the pickup50 and the other is another driving control servo for the motor 51. Acommonly know equalizer and a PRML (partial response maximum likelihood)decoding circuit, which are not shown, can be installed in thedemodulator 54. With respect to an equalizer (waveform equalizer), forexample, a so-called neural net equalizer (that is disclosed in theJapanese Patent No. 2797035) in which a plurality of conversion systemshaving a nonlinear input-output characteristic is combined together withapplying individual variable weighting and constitutes a neural network,a so-called limit equalizer (that is disclosed in the Japanese PatentApplication Laid-open Publication No. 11-259985/1999) in which anamplitude level of reproduced signal is limited to a predetermined valueand forwarded to a filtering process, and a so-called error selectiontype equalizer (that is disclosed in the Japanese Patent ApplicationLaid-open Publication No. 2001-110146) in which an error between areproduced signal and an objective value for waveform equalization isobtained and a frequency of the waveform equalizer is changed adaptivelyso as to minimize the error can be preferably used.

Further, in the commonly known PRML decoding circuit that contains apredicted value controlling and equalization error calculating circuit,a so-called adaptive viterbi decoder (that is disclosed in the JapanesePatent Application Laid-open Publications No. 2000-228064 and No.2001-186027) in which a predicted value utilized for decoding viterbialgorithm is calculated and a frequency response is optimized so as tominimize an equalization error of waveform equalizer can be suitablyused.

Operations of the first reproducing apparatus 500 are explained next.

The first reproducing apparatus 500 is explained hereupon with assumingthat it reproduces user data, which is recorded in a groove “G” of aninformation recording medium 11 having the fourth microscopic pattern3C. The reproducing light 99 is emitted from the light emitting element50 a in the pickup 50 through the objective lens 50 b and converged onthe fourth microscopic pattern 3C of the information recording medium11. Actually, the reproducing light 99 is focused on the fourthmicroscopic pattern 3C, which is provided at a depth of 50 μm to 120 μmthat is equivalent to the thickness of the light transmitting layer 10,and conducted to track the groove “G” thereafter.

The photo detector 50 c receives reflected light from the fourthmicroscopic pattern 3C and reads out a recorded signal. At the moment, atotal sum signal of the photo detector 50 c is transmitted to thedemodulator 54, and then original information is restored thereat. Asmentioned above, reading out a recorded signal is performed by trackingto a groove “G” on the fourth microscopic pattern 3C and reproducing arecord mark “M” that is recorded on the groove “G”.

It is omitted in the above explanation that a focus error signal isnecessary for focusing to be generated and a tracking error signal isnecessary for tracking to be generated.

Such a focus error signal and a tracking error signal are generated by adifferential signal (that is, “(Ia+Ib)−(Ic+Id)”), which is outputtedfrom the 4-division photo detector 50 c in the radial direction, andtransmitted to the servo controller 52. In the servo controller 52, afocus servo signal and a tracking servo signal are generated from thereceived focus error signal and the tracking error signal in accordancewith control by the controller 60, and transmitted to the pickup 50. Inthe meantime, a rotary servo signal is also generated in the servocontroller 52 and transmitted to the motor 51.

Further, in the demodulator 54, the recorded signal is demodulated andapplied with error correction as required, and a data stream that isobtained is transmitted to the I/F 55. Finally, a signal is outputtedexternally in accordance with control by the controller 60.

As mentioned above, the first reproducing apparatus 500 of the presentinvention is loaded with an information recording medium 11 and designedfor coping with the reproducing light 99, which is generated by thelight emitting element 50 a having single wavelength λ within the rangeof 350 nm to 450 nm, the objective lens 50 b having the numericalaperture NA of 0.75 to 0.9 and the 4-division photo detector 50 c.Therefore, the first reproducing apparatus 500 can preferably reproducethe information recording medium 11.

The first reproducing apparatus 500 is such a reproducing apparatus thatreads out user data, which is recorded on the recording layer 9, and canreproduce contents, which are continuously recorded for a long period oftime. It can be used for reproducing an HDTV program and a movie, whichare recorded by video equipment, for example.

With referring to FIG. 30, a second reproducing apparatus according tothe present invention is explained.

In FIG. 30, a second reproducing apparatus 510 is identical to the firstreproducing apparatus 500 except for an address information demodulator56, which is provided between the pickup 50 and the controller 60 anddemodulates an address information that is read out by the pickup 50.The second reproducing apparatus 510 is used for index reproduction of aHDTV program and a movie, which are recorded by video equipment, and forindex reproduction of a computer that stores data.

As mentioned above, a signal that is transmitted from the pickup 50 tothe demodulator 54 is the total sum signal “(Ia+Ib+Ic+Id)” of the4-division photo detector 50 c. On the other hand, another signal thatis transmitted from the pickup 50 to the address information demodulator56 is the differential signal “(Ia+Ib)−(Ic+Id)” in the radial directionof the 4-division photo detector 50 c. Address information is formed inthe information recording medium 11 as a wobbling groove. The wobblingis formed in the radial direction, so that the address signal can beextracted by monitoring the differential signal.

With respect to an actual constitution of the address informationdemodulator 56, it is constituted by at least any one of anamplitude-shift keying modulation demodulator, a frequency-shift keyingmodulation demodulator and a phase-shift keying modulation demodulator.

More accurately, an envelope detector circuit can be suitably used forthe amplitude-shift keying modulation demodulator. A frequency detectorcircuit and a synchronous detector circuit can be suitably used for thefrequency-shift keying modulation demodulator. A synchronous detectorcircuit, a delay detector circuit and an envelope detector circuit canbe suitably used for the phase-shift keying modulation demodulator.

The amplitude-shift keying modulation wave 250, the frequency-shiftkeying modulation wave 260 and the phase-shift keying modulation wave270, which constitute an auxiliary signal area are inputted to theaddress information demodulator 56 and address information isdemodulated from the differential signal in the radial direction of the4-division photo detector 50 c.

The total sum signal may leak into the differential signal in the radialdirection although it may be a small amount. In order to avoid suchleaking, a band-pass filter that is adjusted for a frequency range of anauxiliary signal can be inserted between the pickup 50 and the addressinformation demodulator 56.

Operations of the second reproducing apparatus 510 are explained next.

The second reproducing apparatus 510 is explained hereupon with assumingthat it reproduces address information, which is formed on a groove “G”of an information recording medium 11 having the fourth microscopicpattern 3C, and user data, which is recorded in a recording layer 9 ofthe information recording medium 11. The reproducing light 99 is emittedfrom the light emitting element 50 a in the pickup 50 through theobjective lens 50 b and converged on the fourth microscopic pattern 3Cof the information recording medium 11. Actually, the reproducing light99 is focused on the fourth microscopic pattern 3C, which is provided ata depth of 50 μm to 120 μm that is equivalent to the thickness of thelight transmitting layer 10, and conducted to track the groove “G”thereafter.

A differential signal is generated by the 4-division photo detector 50 cin the pickup 50 and transmitted to the address information demodulator56, and then address information is read out thereat. At this moment,the read-out address information is compared with an address forindexing data, which is inputted to the controller 60. In a case thatthe read-out address information and the address for indexing data donot correspond to each other, the controller 60 sends a signal to theservo controller 52 and instructs the servo controller 52 to search. Thesearching is performed such that a number of revolution of the motor 51is reset to a number of revolutions, which corresponds to a radiusbetween the motor 51 and the pickup 50, according to movement in theradial direction of the pickup 50 while scanning the movement of thepickup 50 in the radial direction.

During a process of scanning, an address outputted from the addressinformation demodulator 56, which receives a differential signal fromthe pickup 50, is compared with a predetermined address. The searchingcontinues until they coincide with each other. When they coincide,scanning in the radial direction is interrupted and reproduction isswitched over to continuous reproduction. An output from the demodulator54, which is inputted with the total sum signal (Ia+Ib+Ic+Id), isresulted in demodulating a data stream that is obtained by indexing andthe output is inputted to the interface (I/F) 55. Finally, the I/F 55outputs a signal externally in accordance with controlling of thecontroller 60.

As mentioned above, the second reproducing apparatus 510 of the presentinvention is loaded with an information recording medium 11 and designedfor coping with the reproducing light 99, which is generated by thelight emitting element 50 a having single wavelength λ within the rangeof 350 nm to 450 nm, the objective lens 50 b having the numericalaperture NA of 0.75 to 0.9. Therefore, the second reproducing apparatus510 can preferably reproduce the information recording medium 11. At thesame time, the second reproducing apparatus 510 can perform indexreproduction of a data stream by reproducing an address thereto.

With referring to FIG. 31, a recording apparatus according to anembodiment of the present invention is described next.

Constitution-wise, a recording apparatus 600 is equivalent to the secondreproducing apparatus 510 except for a circuit that processes a signalto be recorded. Therefore, detailed explanations for the same componentswill be omitted.

As shown in FIG. 31, the recording apparatus 600 is equivalent to thesecond reproducing apparatus 510 shown in FIG. 22 except for that thedemodulator 54 is replaced by a modulator 82 for modulating an originaldata and a waveform converter 83 for transforming a modulated signalfrom the modulator 82 into a waveform suitable for recording on aninformation recording medium 11, which are connected in series. Furtherthe I/F 55 is replaced by an interface (I/F) 81 for receiving anexternal signal to be recorded.

The recording apparatus 600 is an apparatus for recording a computerdata, for example, at a predetermined address newly or recording a HDTVprogram or a movie continuously from a predetermined address by a videorecorder.

The modulator 82 is such a modulator that converts an 8-bit originaldata into 16 bits, in the case of the EFM plus modulation system. Thewaveform converter 83 transforms a modulated signal that is receivedfrom the modulator 82 into a waveform that is suitable for recording onan information recording medium 11.

Actually, the waveform converter 83 is such a converter that converts amodulated signal into a recording pulse, which satisfies a recordingcharacteristic of the recording layer 9 of the information recordingmedium 11. In a case that the recording layer 9 is composed of a phasechange material, for example, a so-called multi-pulse is formed. Inother words, the modulated signal is divided into a unit of channel bitsor less and recording power is changed into a rectangular waveform,wherein peak power, bottom power, erase power and a pulse time duration,which constitute a multi-pulse, are adjusted in accordance with adirection of a controller 60.

Operations of the recording apparatus 600 are explained next.

The recording apparatus 600 is explained hereupon with assuming that itreads out address information, which is formed on a body of a groove “G”in an information recording medium 11 having the fourth microscopicpattern 3C, and records user data on a recording layer 9 in accordancewith the address information.

Reproducing light 99 is emitted from the light emitting element 50 a ofthe pickup 50 through the objective lens 50 b and converged on thefourth microscopic pattern 3C in the information recording medium 11.

Actually, the reproducing light 99 is focused on the fourth microscopicpattern 3C, which is provided at a depth of 50 μm to 120 μm that isequivalent to the thickness of the light transmitting layer 10, andconducted to track the groove “G”. Succeedingly, the differential signal“(Ia+Ib)−(Ic+Id)” in the radial direction that is outputted from thepickup 50 is transmitted to the address information demodulator 56 andaddress information is read out therein. The address information iscompared with an address for indexing data that is inputted to thecontroller 60 thereat.

In a case that they do not correspond to each other, the controller 60sends a signal to the servo controller 52 and instructs the servocontroller 52 to search.

Searching is performed such that a number of revolutions of the motor 51is reset to a number of revolutions, which is suitable for a radiusbetween the motor 51 and the pickup 50, according to movement in theradial direction of the pickup 50 while scanning the movement of thepickup 50 in the radial direction. During a process of scanning, anaddress outputted from the address information demodulator 56, whichreceives a differential signal from the pickup 50, is compared with apredetermined address. The searching is continued until the outputtedaddress and the predetermined address coincide with each other. Whenthey coincide with each other, scanning in the radial direction isinterrupted and switched over to a recording operation. In other words,data, which is outputted from the I/F 81 and inputted to the modulator82, is modulated by the modulator 82 in accordance with controlling ofthe controller 60. Successively, the data that is modulated by themodulator 82 in accordance with the controlling of the controller 60 isinputted to the waveform converter 83 and transformed into a format thatis suitable for recording, and then outputted to the pickup 50.

In the pickup 50, recording light 89 is generated by altering a lightbeam, which is emitted by the light emitting element 50 a, to arecording power that is designated by the waveform converter 83 andirradiated on the information recording medium 11. Consequently,original data is recorded at a predetermined address of the informationrecording medium 11. It is possible to read out the differential signal“(Ia+Ib)−(Ic+Id)” in the radial direction by the recording light 89 andan address can be extracted from the address information demodulator 56while recording. Therefore, recording in a limited area up to a certainaddress that is desired by a user can be realized.

A format of a signal that is used for recording can be applicable foreither the mark position recording method or the mark edge recordingmethod. Further, as mentioned above, the signal that is used forrecording is a so-called (d, k) code, which is defined as that a minimummark length is “d+1” and a maximum mark length is “k+1”, wherein eithera fixed length code or a variable length code can be applied for the (d,k) modulation signal.

As mentioned above, the recording apparatus 600 of the present inventionis loaded with an information recording medium 11 and designed forcoping with the reproducing light 99 and the recording light 89, whichare generated by the light emitting element 50 a having singlewavelength λ within the range of 350 nm to 450 nm and the objective lens50 b having the numerical aperture NA of 0.75 to 0.9. Therefore, therecording apparatus 600 can preferably record on the informationrecording medium 11 as well as enabling arbitrary positioning forrecording by reproducing an address thereto.

While the invention has been described above with reference tofundamental areas thereof, it is apparent that many changes,modifications and variations in the arrangement of equipment and devicesand in materials can be made without departing from the inventionconcept disclosed herein. Further, with respect to the reproducingapparatuses 500 and 510 and the recording apparatus 600 of the presentinvention, it should be understood that the reproducing apparatuses 500and 510 and the recording apparatus 600 include each operation of themother than constitutions and subject matters disclosed in claims.Furthermore, the reproducing apparatuses 500 and 510 and the recordingapparatus 600 include a reproducing method and a recording method, whichare conducted by replacing each operations of them with each step ofprocedures. Moreover, it should be also understood that the reproducingapparatuses 500 and 510 and the recording apparatus 600 include acomputer program that executes each step of the reproducing method andanother computer program that executes each step of the recordingmethod.

An information recording medium according to the present invention isdetailed to preferred embodiments in comparison with comparativeexamples.

Embodiment 1

A phase change recording type information recording medium 11(hereinafter referred to as information recording medium 11) indisciform, which is recorded and reproduced by the recording apparatus600 shown in FIG. 31 and the reproducing apparatus 510 shown in FIG. 30,is prepared, wherein the recording apparatus 600 and the reproducingapparatus 510 are equipped with an optical pickup 50 having wavelength λof 405 nm and numerical aperture NA of 0.85 (where S=λ/NA=476 nm).

In the information recording medium 11 according to the embodiment 1, asubstrate 8 is made by polycarbonate having thickness of 1.1 mm. Arecording layer 9 is composed of Ag₉₈Pd₁Cu₁ and ZnSSiO₂ (in a ratio of80:20 at mol %), which are used along with AgInSbTe, and formed bylaminating AgPdCu, ZnSSiO₂, AgInSbTe and ZnSSiO₂ in order on thesubstrate 8 by the sputtering method. A light transmitting layer 10 isformed by sticking polycarbonate sheet having thickness of 0.095 mm onthe recording layer 9 through UV ray curable type transparent adhesivehaving thickness of 0.005 mm. A refractive index “n” of the lighttransmitting layer 10 is 1.6.

Address information is modulated and formed in a wobble shape on aconvex shaped section of the recording layer 9 viewed from the lighttransmitting layer 10 side. Both sidewalls of the convex shaped sectionare in synchronism with each other and in phase and formed in like afourth microscopic pattern 3C shown in FIG. 16. In other words, theconvex shaped section is formed such that both the sidewalls are inparallel to each other. The convex shaped section is identical to thefourth microscopic pattern 3C shown in FIG. 17 and formed in such thatthe pitch “P” satisfies an inequality P≦S and the wobbling width A inpeak to peak value satisfies another inequality 0.01 S≦Δ≦0.15 S.

More accurately, the fourth microscopic pattern 3C is formed so as to bethat P=320 nm, Δ=54 nm and elevation difference between a concave shapedsection and a convex shaped section of the fourth microscopic pattern 3Cis 23 nm. Further, a modulated wobble is composed of the frequency-shiftkeying modulation wave 262 shown in FIG. 24, which is constituted by asine wave (or a cosine wave) as a fundamental wave. Its phase differencefrom the reference phase is 2π±(π/2.5) and a phase is selected for awave so as to be continuous at a point where a frequency is changedover.

Furthermore, the recording layer 9 is initialized by changing phase ofthe recording layer 9 from an amorphous state in low reflectivity to acrystalline state in high reflectivity by irradiating a laser beam fromthe side of the light transmitting layer 10.

Recording on the information recording medium 11 according to theembodiment 1 is explained next.

The information recording medium 11 according to the embodiment 1 isloaded into the recording apparatus 600 shown in FIG. 31 that isequipped with the pickup 50 having wavelength λ of 405 nm and numericalaperture NA of 0.85. A differential signal that is reproduced from aconvex shaped section (groove “G”), which projects into the lighttransmitting layer 10 side, is conducted to the address informationdemodulator 56. While comparing address information obtained thereinwith a desired address, the pickup 50 is guided to the desired address,and then a record mark “M” is recorded on the recording layer 9 at aconvex shaped section (groove “G”) that projects into the lighttransmitting layer 10 by the (d, k) coding method. In this process, the(d, k) coding method is the 17PP modulation system and a minimum marklength (equal to 2T) of the record mark “M” is 0.149 μm.

Recording conditions are as follows: recording peak power is 6.0 mW,bias power is 2.6 mW, each bottom power of among multi-pulses and acooling pulse is 0.1 mW and linear velocity is 5.3 m/s. Further, therecording is a recording method of converting a modulated signal into aso-called multi-pulse by the waveform converter 83. The recording methodadopts the 3-value power modulation system, which defines such that eachwidth of head pulse and a succeeding pulse is equal to 0.4 time as longas one recording period 1T and width of a cooling pulse is equal to 0.4time as long as one recording period 1T.

The information recording medium 11 that is recorded as mentioned aboveis evaluated as follows.

The information recording medium 11 according to the embodiment 1 isloaded into the second reproducing apparatus 510 shown in FIG. 30, whichis equipped with the pickup 50 having wavelength λ of 405 nm andnumerical aperture NA of 0.85, and evaluated by reproducing a convexshaped section (groove “G”), which projects into the light transmittinglayer 10 side. A signal having modulation amplitude (equal to“(I8H−I8L)/I8H”) of 0.52 is obtained from a total sum signal of thepickup 50. Further, a reproduced signal, which is obtained form theaddress information demodulator 54, is excellent in error rate as low as2×10⁻⁵ and it is found that data without any problems in practicalapplication can be extracted. An error rate of address information thatis obtained from the address information demodulator 56 is the order of1% in a recorded portion and address data can be restored excellently.If an error rate of address information is less than 5% whilereproducing after recording on the recording layer 9, data in littleerror can be restored by a process of error correction. Therefore, theerror rate of address information in the order of 1% is extremelysuitable for processing.

A manufacturing method of the substrate 8 is explained hereupon.

As shown in FIG. 1, a flat substrate 1, which is finished in flat asfine as the optical grade and is in a state of soda lime glass(containing 70% of silicon oxide), is prepared, and then, as shown inFIG. 2, a positive type energy ray sensitive film 2 is coated evenly onthe surface of the flat substrate 1. The positive type energy raysensitive film 2 decomposes through two steps when irradiated by anenergy ray. A mixed material of cresol novolac resin and naphthoquinonediazide is used for the positive type energy ray sensitive film 2.

By using the first energy ray radiating apparatus 30 shown in FIG. 12, afrequency-shift keying modulation wave 262 is inputted to the beamshaper 122 through a processor, not shown, externally and a convergedenergy ray is irradiated on the positive type energy ray sensitive film2. Further, the energy ray source 121 is a laser device that emits lighthaving wavelength of 266 nm and the beam shaper 122 is an electroopticaldeflection apparatus (EOD), which is composed of an electroopticalcrystal element and deflects a converged energy ray to the radialdirection in response to a modulated signal of address. Thus, as shownin FIG. 11, the first microscopic pattern 3 is recorded so as for eachperiod and phase of wobbles on both sides of groove “G” to be equal toeach other. The first microscopic pattern 3 shown in FIG. 3 is formedafter forming a groove “G” having an address wobble through the alkalideveloping process.

As shown in FIG. 4, a first plating layer 4 that is composed of nickelhaving thickness of 250 nm is formed on the flat substrate 1 that isformed with the first microscopic pattern 3 through a thin conductivelayer (not shown). Then, as shown in FIG. 5, a first plating die 5having a second microscopic pattern 3A is produced by peeling the firstplating layer 4 from the flat substrate 1.

A second plating layer 6 is formed on the first plating die 5 having thesecond microscopic pattern 3A, as shown in FIG. 6. As shown in FIG. 7, asecond plating die 7 having a third microscopic pattern 3B (made bynickel and 300 μm thick) is produced by peeling the second plating layer6 from the first plating die 5.

Mounting the second plating die 7 on an injection molding machine,injecting melted polycarbonate resin into the second plating die 7 andcooling down manufactures a substrate 8 shown in FIG. 8. On the surfaceof the substrate 8, a fourth microscopic pattern 3C that is reverselytransferred from the second plating die 7 having the third microscopicpattern 3B is formed.

Embodiment 2

An information recording medium 11 according to an embodiment 2 isidentical to that of the embodiment 1 except for that the (d, k) codingmethod is replaced by the “D4, 6” modulation system and the minimum marklength (equal to 2T) is 0.154 μm. Further, the information recordingmedium 11 of the embodiment 2 is evaluated by reproducing a convexshaped section that projects into the light transmitting layer 10 afterrecording on the convex shape section as mentioned above. A signalhaving modulated amplitude (equal to “(I10H−I10L)/I10H”) of 0.60 isobtained. Furthermore, a reproduced signal, which is obtained from theaddress information demodulator 54, is excellent in error rate as low as8×10⁻⁶ and it is found that data without any problems in practicalapplication can be extracted. Moreover, an error rate of addressinformation is the order of 1% in a recorded portion and address datacan be restored excellently.

Embodiment 3

An information recording medium 11 according to an embodiment 3 isidentical to that of the embodiment 1 except for that the (d, k) codingmethod is replaced by the “D8-15” modulation system and the minimum marklength (equal to 3T) is 0.185 μm. Further, the information recordingmedium 11 of the embodiment 3 is evaluated by reproducing a convexshaped section that projects into the light transmitting layer 10 afterrecording on the convex shape section as mentioned above. A signalhaving modulated amplitude (equal to “(I12H−I12L)/I12H”) of 0.63 isobtained. Furthermore, a reproduced signal, which is obtained from theaddress information demodulator 54, is excellent in error rate as low as4×10⁻⁶ and it is found that data without any problems in practicalapplication can be extracted. Moreover, an error rate of addressinformation is the order of 1% in a recorded portion and address datacan be restored excellently.

Embodiment 4

An information recording medium 11 according to an embodiment 4 isidentical to that of the embodiment 1 except for that addressinformation is recorded on a convex shaped section (groove “G”), whichprojects into the light transmitting layer 10, as a wobble by aphase-shift keying modulation wave 272. Further, the informationrecording medium 11 of the embodiment 4 is evaluated by reproducing aconvex shaped section that projects into the light transmitting layer 10after recording on the convex shape section as mentioned above. A signalhaving modulated amplitude (equal to “(I8H−I8L)/I8H”) of 0.52 isobtained. Furthermore, a reproduced signal, which is obtained from theaddress information demodulator 54, is excellent in error rate as low as2×10⁻⁵ and it is found that data without any problems in practicalapplication can be extracted. Moreover, an error rate of addressinformation is the order of 0.1% in a recorded portion and address datacan be restored excellently.

Embodiment 5

A phase change recording type information recording medium 11(hereinafter referred to as information recording medium 11) indisciform, which is recorded and reproduced by the recording apparatus600 shown in FIG. 31 and the reproducing apparatus 510 shown in FIG. 30,is prepared, wherein the recording apparatus 600 and the reproducingapparatus 510 are equipped with an optical pickup 50 having wavelength λof 405 nm and numerical aperture NA of 0.85 (where S=λ/NA=476 nm)respectively.

Manufacturing the information recording medium 11 of the embodiment 5 isexplained hereinafter.

As shown in FIG. 1, a flat silicon substrate 1, which is finished inflat as fine as the optical grade, is prepared, and then, as shown inFIG. 2, a negative type energy ray sensitive film 2 is coated evenly onone surface of the flat silicon substrate 1. The negative type energyray sensitive film 2 becomes insoluble through two steps when irradiatedby an energy ray. A bridged acrylate resin is used for the negative typeenergy ray sensitive film 2.

By using the second energy ray radiating apparatus 40 shown in FIG. 13,a frequency-shift keying modulation wave 262 is inputted to the beamshaper 122 through a processor, not shown, externally and a convergedenergy ray is irradiated on the negative type energy ray sensitive film2. Further, the energy ray source 121 is an electron-beam irradiatingapparatus and the beam shaper 122 is a beam deflecting device, whichdeflects a converged energy ray to the radial direction in response to amodulated signal of address. Thus, as shown in FIG. 11, the firstmicroscopic pattern 3 is recorded so as for each period and phase ofwobbles on both sides of land “L” to be equal to each other.

A land “L” having an address wobble is formed through a developingprocess by organic solvent. The land “L” is formed in dimensions suchthat the pitch “P” satisfies an inequality P≦S and the wobbling width Δin peak to peak value satisfies another inequality 0.01S≦Δ≦0.15S.Exactly, it is formed so as to be that P=320 nm and Δ=54 nm. Further, amodulated wobble is composed of the frequency-shift keying modulationwave 262 shown in FIG. 24, which is constituted by a sine wave (or acosine wave) as a fundamental wave. Its phase difference from thereference phase is 2π±(π/2.5) and a phase is selected for a wave so asto be continuous at a point where a frequency is changed over.

By plating nickel in 300 μm thick through a thin conductive film andpeeling off the nickel plating layer, as shown in FIG. 14, a thirdplating die 12 (of nickel in 250 μm thick) having a fifth microscopicpattern 3D is formed.

Mounting the third plating die 12 on an injection molding machine,injecting melted polycarbonate resin into the third plating die 12 andcooling down manufactures a substrate 8 shown in FIG. 15. On the surfaceof the substrate 8, a sixth microscopic pattern 3E that is reverselytransferred from the third plating die 12 having the fifth microscopicpattern 3D is formed.

Succeedingly, as shown in FIGS. 9 and 10, a recording layer 9 and alight transmitting layer 10 are formed. A forming method of these layersis identical to that of the embodiment 1. In the completed informationrecording medium 11, the recording layer 9 is initialized by changingphase of the recording layer 9 from an amorphous state in lowreflectivity to a crystalline state in high reflectivity by irradiatinga laser beam from the side of the light transmitting layer 10.

Recording on the information recording medium 11 according to theembodiment 5 is explained next.

The information recording medium 11 according to the embodiment 5 isloaded into the recording apparatus 600 shown in FIG. 31 that isequipped with the pickup 50 having wavelength λ of 405 nm and numericalaperture NA of 0.85. A differential signal that is reproduced from aconvex shaped section (land “L”), which projects into the lighttransmitting layer 10 side, is conducted to the address informationdemodulator 56. While comparing address information obtained thereinwith a desired address, the pickup 50 is guided to the desired address,and then a record mark “M” is recorded on the recording layer 9 at aconvex shaped section (land “L”) that projects into the lighttransmitting layer 10 by the (d, k) coding method. In this process, the(d, k) coding method is the 17PP modulation system and a minimum marklength (equal to 2T) of the record mark “M” is 0.149 μm.

Recording conditions are as follows: recording peak power is 6.0 mW,bias power is 2.6 mW, each bottom power of among multi-pulses and acooling pulse is 0.1 mW and linear velocity is 5.3 m/s. Further, therecording is performed by a recording method that converts a modulatedsignal into a so-called multi-pulse by the waveform converter 83. Therecording method adopts the 3-value power modulation system, whichdefines such that each width of head pulse and succeeding pulses isequal to 0.4 time as long as one recording period 1T and width of acooling pulse is equal to 0.4 time as long as one recording period 1T.

The information recording medium 11 of the embodiment 5 that is recordedas mentioned above is evaluated as follows.

The information recording medium 11 according to the embodiment 5 isloaded into the second reproducing apparatus 510 shown in FIG. 30, whichis equipped with the pickup 50 having wavelength λ of 405 nm andnumerical aperture NA of 0.85, and evaluated by reproducing a convexshaped section (land “L”), which projects into the light transmittinglayer 10 side. A signal having modulation amplitude (equal to“(I8H−I8L)/I8H”) of 0.53 is obtained from a total sum signal of thepickup 50. Further, a reproduced signal, which is obtained form theaddress information demodulator 54, is excellent in error rate as low as2.1×10⁻⁵ and it is found that data without any problems in practicalapplication can be extracted. An error rate of address information thatis obtained from the address information demodulator 56 is the order of1% in a recorded portion and address data can be restored excellently.

As mentioned above, it is found that each information recording medium11 of the embodiments 1 through 5 can obtain sufficient modulationamplitude and sufficiently suppress an error rate. Further, it is alsofound that an address signal can be demodulated excellently.

Comparative examples 1 and 2 are explained next.

COMPARATIVE EXAMPLE 1

An information recording medium according to a comparative example 1 ismanufactured by the same manufacturing method as the embodiment 1 exceptfor that a substrate 8 is formed by the injection molding method byusing the first plating die 5 having the second microscopic pattern 3A.The manufacturing method for the comparative example 1 is the samemanufacturing method as the stamper method that is used formanufacturing a DVD disc.

By using the recording apparatus 600 shown in FIG. 31, the informationrecording medium that is manufactured as mentioned above is recordedselectively on a convex shaped section, which projects into the lighttransmitting layer 10, by the (d, k) coding method as same manner as theembodiment 1. Then an address is reproduced by the recording apparatus600 on trial. According to the trial reproduction, address informationis incoherent.

The information recording medium of the comparative example 1 isevaluated by reproducing the convex shaped section by using thereproducing apparatus 510 shown in FIG. 30.

According to the evaluation, address information is incoherent, so thatit is impossible to perform positioning by an address, which isessentially obtained from the address information. This is caused bythat each period and each phase of both sidewalls of the convex shapedsection are not equal to each other, that is, not parallel to eachother. Consequently, different addresses interfere with each other andthey are reproduced at the same time.

By reproducing areas having approximately the same radius by the secondreproducing apparatus 510 shown in FIG. 30, a signal having modulationamplitude (equal to “(I8H−I8L)/I8H”) of 0.52 is obtained from a totalsum signal of the pickup 50 although positioning can not be performed.Further, a reproduced signal, which is obtained form the addressinformation demodulator 54, is excellent in error rate as low as 2×10⁻⁵and it is found that data without any problems in practical applicationcan be extracted. However, address information that is obtained from theaddress information demodulator 56 is interfered and incoherent data asthe same condition as the trail reproduction by the recording apparatus600 mentioned above.

Accordingly, the information recording medium of the comparative example1 is resulted in defective.

COMPARATIVE EXAMPLE 2

An information recording medium according to a comparative example 2 ismanufactured by the same manufacturing method as the comparativeexample 1. By using the recording apparatus 600, the informationrecording medium that is manufactured as mentioned above is recordedselectively on a convex shaped section, which projects into the lighttransmitting layer 10, by the (d, k) coding method as same manner as theembodiment 1. In this case, address information is correctlydemodulated, so that it is revealed that recording by correctpositioning can be performed.

Then the recorded information recording medium is evaluated byreproducing the convex shaped section by using the reproducing apparatus510 shown in FIG. 30. Address information that is obtained from adifferential signal of the pickup 50 in the address informationdemodulator 56 is the order of 1% in a recorded portion and address datacan be restored excellently.

On the contrary, a weak signal of which modulation amplitude (equal to“(I8H−I8L)/I8H”) is the order of 0.37 is obtained from a total sumsignal of the pickup 50. Further, an error rate of reproduced signal,which is obtained form the address information demodulator 54, is2×10⁻³. Consequently, data that is full of errors is reproduced.

Accordingly, the information recording medium of the comparative example2 is defective.

As exhibited in the embodiments 1 through 5 and the comparative examples1 and 2, by using the information recording medium 11, which is composedof the light transmitting layer 10 having thickness within a range of0.05 mm to 0.12 mm and recorded with address information that ismodulated so as to be the same period and phase on both sidewalls of aconvex shaped section that projects into the light transmitting layer10. Further, by recording on and reproduced from the convex shapedsection, the information recording medium 11 can be an ideal informationrecording medium that satisfies all parameters of recording on therecording layer 9 such as modulation amplitude, an error rate and anaddress error rate totally.

EFFECTS OF INVENTION

According to an aspect of the present invention, there provided aninformation recording medium, which can be recorded with information ona convex shaped section, which is viewed from a side that is irradiatedwith a laser beam. A reproduced signal in high output and high qualitycan be obtained, so that recording and reproducing in low error rate andhigh density can be realized. Further, each wobbling period and phase ofboth sidewalls of a convex shaped section, which is viewed from a sidethat is irradiated with a laser beam, are equal to each other, so thatinterference is eliminated and resulted in reproducing accurate addressinformation.

It should be understood that many modifications and adaptations of theinvention will become apparent to those skilled in the art and it isintended to encompass such obvious modifications and changes in thescope of the claims appended hereto.

1. An information recording medium comprising: a substrate having amicroscopic pattern, which includes a shape of continuous substance ofapproximately parallel grooves formed with a convex shaped section and aconcave shaped section alternating on a surface of the substrate; arecording layer formed on the microscopic pattern; and a lighttransmitting layer having thickness of 0.05 mm to 0.12 mm formed on therecording layer, the microscopic pattern satisfying a relation ofP≦λ/NA, wherein P is a pitch of the convex shaped section, λ is awavelength of a reproducing light beam and NA is a numerical aperture ofan objective lens, and further wherein the microscopic pattern includesa modulated address information formed on both side walls of the convexshaped section viewed from the light transmitting layer as a wobble,both the side walls being parallel to each other, and furthermorewherein the information recording medium is installed in a cartridge. 2.An information recording medium comprising: a substrate having amicroscopic pattern, which includes a shape of continuous substance ofapproximately parallel grooves formed with a convex shaped section and aconcave shaped section alternating on a surface of the substrate; arecording layer formed on the microscopic pattern; and a lighttransmitting layer having thickness of 0.05 mm to 0.12 mm formed on therecording layer, the microscopic pattern satisfying a relation ofP≦λ/NA, wherein P is a pitch of the convex shaped section, λ is awavelength of a reproducing light beam and NA is a numerical aperture ofan objective lens, and further wherein the microscopic pattern includesa modulated address information formed on both side walls of the convexshaped section viewed from the light transmitting layer as a wobblehaving a same period and phase with respect to both the side walls, andfurthermore wherein the convex shaped section is formed by the constantangular velocity (CAV) method.
 3. A reproducing apparatus forreproducing an information recording medium comprising: a substratehaving a microscopic pattern, which includes a shape of continuoussubstance of approximately parallel grooves formed with a convex shapedsection and a concave shaped section alternating on a surface of thesubstrate; a recording layer formed on the microscopic pattern; and alight transmitting layer having thickness of 0.05 mm to 0.12 mm formedon the recording layer, the microscopic pattern satisfying a relation ofP≦λ/NA, wherein P is a pitch of the convex shaped section, λ is awavelength of a reproducing light beam and NA is a numerical aperture ofan objective lens, and further wherein the microscopic pattern includesa modulated address information formed on both side walls of the convexshaped section viewed from the light transmitting layer as a wobble,both the side walls being parallel to each other, the reproducingapparatus at least comprising: a motor for rotating the informationrecording medium; and a turntable for supporting the informationrecording medium.